Windows 7

"GNU/Linux" redirects here. For the "GNU" part, see GNU/Linux naming controversy.

Linux

Developer	Linus Torvalds and thousands of collaborators
Written in	C
OS family	Unix-like
Working state	Current
Source model	Free and open source software
Marketing target	Desktops, servers, embedded devices
Available in	Multi-lingual
Platforms	IA-32, MIPS, x86-64, SPARC, DEC Alpha, Itanium, PowerPC, ARM, m68k, PA-RISC, s390, SuperH, M32R and more
Kernel type	Monolithic
Userland	GNU and others
Default user interface	Graphical (X Window System)
License	Various including GNU General Public License, BSD License, Apache License, MIT License, and others
Official website	www.kernel.org

Linux (commonly Template:Pron-en LIN-əks in American English, also Template:Pron-en LIN-ooks in Europe and Canada) is a generic term referring to Unix-like computer operating systems that use the Linux kernel. Their development is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified, and redistributed, both commercially and non-commercially, by anyone under licenses such as the GNU General Public License.

Linux can be installed on a wide variety of computer hardware, ranging from embedded devices such as mobile phones, smartphones and wristwatches to mainframes and supercomputers. Linux is predominantly known for its use in servers; in 2007 Linux's overall share of the server market was estimated at 12.7%, while a 2008 estimate suggested that 60% of all web servers ran Linux. Most desktop computers run either Mac OS X or Microsoft Windows, with Linux having only 1–2% of the desktop market. However, desktop use of Linux has become increasingly popular in recent years, partly owing to the popular Mandriva Linux, Fedora, Debian or Ubuntu distributions and the emergence of netbooks and smartbooks.

Typically Linux is packaged in a format known as a Linux distribution for desktop and server use. Linux distributions include the Linux kernel and all of the supporting software required to run a complete system, such as utilities and libraries, the X Window System, the GNOME and KDE desktop environments, and the Apache HTTP Server. Commonly-used applications with desktop Linux systems include the Mozilla Firefox web-browser, the OpenOffice.org office application suite and the GIMP image editor.

The name "Linux" comes from the Linux kernel, originally written in 1991 by Linus Torvalds. The main supporting Userland in the form of system tools and libraries from the GNU Project (announced in 1983 by Richard Stallman) is the basis for the Free Software Foundation's preferred name GNU/Linux.

History

See also: History of Linux

Unix

The Unix operating system was conceived and implemented in 1969 at AT&T's Bell Laboratories in the United States by Ken Thompson, Dennis Ritchie, Douglas McIlroy, and Joe Ossanna. Unix derived its name as a joke and reference to an experimental operating system that was slow and ineffective called MULTICS. It was first released in 1971 and was initially entirely written in assembly language, a common practice at the time. Later, in a key pioneering approach in 1973, Unix was re-written in the programming language C by Dennis Ritchie, (with exceptions to the kernel and I/O). The availability of an operating system written in a high-level language allowed easier portability to different computer platforms. With a legal glitch forcing AT&T to license the operating system's source code, Unix quickly grew and became widely adopted by academic institutions and businesses.

GNU

The GNU Project, started in 1983 by Richard Stallman, had the goal of creating a "complete Unix-compatible software system" composed entirely of free software. Work began in 1984. Later, in 1985, Stallman created the Free Software Foundation and wrote the GNU General Public License (GNU GPL) in 1989. By the early 1990s, many of the programs required in an operating system (such as libraries, compilers, text editors, a Unix shell, and a windowing system) were completed, although low-level elements such as device drivers, daemons, and the kernel were stalled and incomplete. Linus Torvalds has said that if the GNU kernel had been available at the time (1991), he would not have decided to write his own.

MINIX

Andrew S. Tanenbaum, author of the MINIX operating system

MINIX was an inexpensive minimal Unix-like operating system, designed for education in computer science, written by Andrew S. Tanenbaum. As of version 3, MINIX is free and redesigned also for “serious” use.

In 1991 while attending the University of Helsinki, Torvalds, curious about the operating systems and frustrated by the licensing of MINIX limiting it to educational use only (which prevented any commercial use) began to work on his own operating system which eventually became Linux.

Torvalds began the development of Linux on MINIX and applications written for MINIX were also used on Linux. Later Linux matured and it became possible for Linux to be developed under itself. Also GNU applications replaced all MINIX ones because, with code from the GNU system freely available, it was advantageous if this could be used with the fledgling operating system. Code licensed under the GNU GPL can be used in other projects, so long as they also are released under the same or a compatible license. In order to make the Linux available for commercial use, Torvalds initiated a switch from his original license (which prohibited commercial redistribution) to the GNU GPL. Developers worked to integrate GNU components with Linux to make a fully functional and free operating system.

Commercial and popular uptake

Main article: Linux adoption

Today Linux distributions are used in numerous domains, from embedded systems to supercomputers, and have secured a place in server installations with the popular LAMP application stack. Use of Linux distributions in home and enterprise desktops has been expanding. They have also gained popularity with various local and national governments. The federal government of Brazil is well known for its support for Linux. News of the Russian military creating their own Linux distribution has also surfaced, and has come to fruition as the G.H.ost Project. The Indian state of Kerala has gone so far as to make it mandatory for all state high schools to run Linux on their computers. China uses Linux exclusively as the operating system for its Loongson processor family to achieve technology independence. In Spain some regions have developed their own Linux distributions, which are widely used in education and official institutions, like gnuLinEx in Extremadura and Guadalinex in Andalusia. France and Germany have also taken steps towards the adoption of Linux.

Linux distributions have also become popular with the newly founded netbook market, with many devices such as the ASUS Eee PC and Acer Aspire One shipping with customized Linux distributions installed.

Current development

Torvalds continues to direct the development of the kernel. Stallman heads the Free Software Foundation, which in turn supports the GNU components. Finally, individuals and corporations develop third-party non-GNU components. These third-party components comprise a vast body of work and may include both kernel modules and user applications and libraries. Linux vendors and communities combine and distribute the kernel, GNU components, and non-GNU components, with additional package management software in the form of Linux distributions.

Design

A Linux-based system is a modular Unix-like operating system. It derives much of its basic design from principles established in Unix during the 1970s and 1980s. Such a system uses a monolithic kernel, the Linux kernel, which handles process control, networking, and peripheral and file system access. Device drivers are either integrated directly with the kernel or added as modules loaded while the system is running.

Separate projects that interface with the kernel provide much of the system's higher-level functionality. The GNU userland is an important part of most Linux-based systems, providing the most common implementation of the C library, a popular shell, and many of the common Unix tools which carry out many basic operating system tasks. The graphical user interface (or GUI) used by most Linux systems is built on top of an implementation of the X Window System.

User interface

See also: User interface

Users can control a Linux-based system through a command line interface (or CLI), a graphical user interface (or GUI), or through controls attached to the associated hardware (this is common for embedded systems). For desktop systems, the default mode is usually graphical user interface, where the CLI is available through terminal emulator windows or on a separate virtual console.

On desktop machines, KDE, GNOME, and Xfce are the most popular user interfaces, though a variety of additional user interfaces exist. Most popular user interfaces run on top of the X Window System (often simply called "X"), which provides network transparency, enabling a graphical application running on one machine to be displayed and controlled from another.

Other GUIs include X window managers such as FVWM, Enlightenment, and Window Maker. The window manager provides a means to control the placement and appearance of individual application windows, and interacts with the X Window System. This is a more minimalist goal than KDE, GNOME et al., which are termed desktop environments.

A Linux system typically provides a CLI through a shell, which is the traditional way of interacting with a Unix system. A Linux distribution specialized for servers may use the CLI as its only interface.

Most low-level Linux components, including the GNU userland, use the CLI exclusively. The CLI is particularly suited for automation of repetitive or delayed tasks, and provides very simple inter-process communication. A graphical terminal emulator program is often used to access the CLI from a Linux desktop.

Development

A summarized history of Unix-like operating systems showing Linux's origins. Note that despite similar architectural designs and concepts being shared as part of the POSIX standard, Linux does not share any non-free source code with the original Unix or MINIX.

Main article: Linux distribution

The primary difference between Linux and many other popular contemporary operating systems is that the Linux kernel and other components are free and open source software. Linux is not the only such operating system, although it is by far the most widely used. Some free and open source software licenses are based on the principle of copyleft, a kind of reciprocity: any work derived from a copyleft piece of software must also be copyleft itself. The most common free software license, the GNU GPL, is a form of copyleft, and is used for the Linux kernel and many of the components from the GNU project.

Linux based distributions are intended by developers for interoperability with other operating systems and established computing standards. Linux systems adhere to POSIX, SUS, ISO, and ANSI standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT.

Free software projects, although developed in a collaborative fashion, are often produced independently of each other. The fact that the software licenses explicitly permit redistribution, however, provides a basis for larger scale projects that collect the software produced by stand-alone projects and make it available all at once in the form of a Linux distribution.

A Linux distribution, commonly called a "distro", is a project that manages a remote collection of system software and application software packages available for download and installation through a network connection. This allows the user to adapt the operating system to his/her specific needs. Distributions are maintained by individuals, loose-knit teams, volunteer organizations, and commercial entities. A distribution is responsible for the default configuration of the installed Linux kernel, general system security, and more generally integration of the different software packages into a coherent whole. Distributions typically use a package manager such as Synaptic, YAST, or Portage to install, remove and update all of a system's software from one central location.

Community

See also: Free software community and Linux Users Group

A distribution is largely driven by its developer and user communities. Some vendors develop and fund their distributions on a volunteer basis, Debian being a well-known example. Others maintain a community version of their commercial distributions, as Red Hat does with Fedora.

In many cities and regions, local associations known as Linux Users Groups (LUGs) seek to promote their preferred distribution and by extension free software. They hold meetings and provide free demonstrations, training, technical support, and operating system installation to new users. Many Internet communities also provide support to Linux users and developers. Most distributions and free software / open source projects have IRC chatrooms or newsgroups. Online forums are another means for support, with notable examples being LinuxQuestions.org and the Gentoo forums. Linux distributions host mailing lists; commonly there will be a specific topic such as usage or development for a given list.

There are several technology websites with a Linux focus. Print magazines on Linux often include cover disks including software or even complete Linux distributions.

Although Linux distributions are generally available without charge, several large corporations sell, support, and contribute to the development of the components of the system and of free software. An analysis of Linux showed 75 percent of the code from December 2008 to January 2010 was developed by programmers working for corporations, leaving about 18 percent to the traditional, open source community. Some of the major corporations that contribute include Dell, IBM, HP, Oracle, Sun Microsystems, Novell, Nokia. A number of corporations, notably Red Hat, have built their entire business around Linux distributions.

The free software licenses, on which the various software packages of a distribution built on the Linux kernel are based, explicitly accommodate and encourage commercialization; the relationship between a Linux distribution as a whole and individual vendors may be seen as symbiotic. One common business model of commercial suppliers is charging for support, especially for business users. A number of companies also offer a specialized business version of their distribution, which adds proprietary support packages and tools to administer higher numbers of installations or to simplify administrative tasks. Another business model is to give away the software in order to sell hardware.

Programming on Linux

Most Linux distributions support dozens of programming languages. The most common collection of utilities for building both Linux applications and operating system programs is found within the GNU toolchain, which includes the GNU Compiler Collection (GCC) and the GNU build system. Amongst others, GCC provides compilers for Ada, C, C++, Java, and Fortran. The Linux kernel itself is written to be compiled with GCC. Proprietary compilers for Linux include the Intel C++ Compiler, Sun Studio, and IBM XL C/C++ Compiler. BASIC is supported in such forms as Gambas, FreeBASIC, and XBasic.

Most distributions also include support for PHP, Perl, Ruby, Python and other dynamic languages. While not as common, Linux also supports C# via the Mono project, sponsored by Novell, and Scheme. A number of Java Virtual Machines and development kits run on Linux, including the original Sun Microsystems JVM (HotSpot), and IBM's J2SE RE, as well as many open-source projects like Kaffe.

The two main frameworks for developing graphical applications are those of GNOME and KDE. These projects are based on the GTK+ and Qt widget toolkits, respectively, which can also be used independently of the larger framework. Both support a wide variety of languages. There are a number of Integrated development environments available including Anjuta, Code::Blocks, Eclipse, KDevelop, Lazarus, MonoDevelop, NetBeans, Qt Creator and Omnis Studio while the long-established editors Vim and Emacs remain popular.

Uses

As well as those designed for general purpose use on desktops and servers, distributions may be specialized for different purposes including: computer architecture support, embedded systems, stability, security, localization to a specific region or language, targeting of specific user groups, support for real-time applications, or commitment to a given desktop environment. Furthermore, some distributions deliberately include only free software. Currently, over three hundred distributions are actively developed, with about a dozen distributions being most popular for general-purpose use.

Linux is a widely ported operating system kernel. The Linux kernel runs on a highly diverse range of computer architectures: in the hand-held ARM-based iPAQ and the mainframe IBM System z9, System z10 in devices ranging from mobile phones to supercomputers. Specialized distributions exist for less mainstream architectures. The ELKS kernel fork can run on Intel 8086 or Intel 80286 16-bit microprocessors, while the µClinux kernel fork may run on systems without a memory management unit. The kernel also runs on architectures that were only ever intended to use a manufacturer-created operating system, such as Macintosh computers (with both PowerPC and Intel processors), PDAs, video game consoles, portable music players, and mobile phones.

There are several industry associations and hardware conferences devoted to maintaining and improving support for diverse hardware under Linux, such as FreedomHEC.

Desktop

GNOME

KDE

Xfce

LXDE

Main article: Desktop Linux

The popularity of Linux on standard desktops (and laptops) has been increasing over the years. Currently most distributions include a graphical user environment. The two most popular such environments are GNOME and KDE, both of which are mature and support a wide variety of languages.

The performance of Linux on the desktop has been a controversial topic; for example in 2007 Con Kolivas accused the Linux community of favoring performance on servers. He quit Linux kernel development because he was frustrated with this lack of focus on the desktop, and then gave a "tell all" interview on the topic. Since then a significant effort has been expended improving the desktop experience. Projects such as upstart aim for a faster boot time. In the field of gaming, the Linux desktop still lags behind Windows. However, there are several companies that do port their own or other companies' games to Linux.

Many types of applications available for Microsoft Windows and Mac OS X are also available for Linux. Commonly, either a free software application will exist which does the functions of an application found on another operating systems, or that application will have a version that works on Linux (such as Skype). Furthermore, the Wine project provides a Windows compatibility layer to run unmodified Windows applications on Linux. CrossOver is a proprietary solution based on the open source Wine project that supports running Windows versions of Microsoft Office, Intuit applications such as Quicken and QuickBooks, Adobe Photoshop versions through CS2, and many popular games such as World of Warcraft and Team Fortress 2. In other cases, where there is no Linux port of some software in areas such as desktop publishing and professional audio, there is equivalent software available on Linux.

Many popular applications are available for a wide variety of operating systems. For example Mozilla Firefox, and OpenOffice.org have downloadable versions for all major operating systems. Furthermore, some applications were initially developed for Linux (such as Pidgin, and GIMP) and, due to their popularity, were ported to other operating systems (including Windows and Mac OS X).

A growing number of proprietary desktop applications are also supported on Linux, see List of proprietary software for Linux. In the field of animation and visual effects, most high end software, such as AutoDesk Maya, Softimage XSI and Apple Shake, is available for Linux, Windows and/or Mac OS X.

The collaborative nature of free software development allows distributed teams to localize Linux distributions for use in locales where localizing proprietary systems would not be cost-effective. For example the Sinhalese language version of the Knoppix distribution was available significantly before Microsoft Windows XP was translated to Sinhalese. In this case the Lanka Linux User Group played a major part in developing the localized system by combining the knowledge of university professors, linguists, and local developers.

Installing new software in Linux is typically done through the use of package managers such as Synaptic Package Manager, PackageKit, and Yum Extender. While major Linux distributions have extensive repositories (tens of thousands of packages), not all the software that can run on Linux is available from the official repositories. Alternatively, users can install packages from unofficial repositories, download pre-compiled packages directly from websites, or compile the source code by themselves. All these methods come with different degrees of difficulty, compiling the source code is in general considered a challenging process for new Linux users, but it's hardly needed in modern distributions.

Servers, mainframes and supercomputers

Servers designed for Linux

Linux distributions have long been used as server operating systems, and have risen to prominence in that area; Netcraft reported in September 2006 that eight of the ten most reliable internet hosting companies ran Linux distributions on their web servers. (As of June 2008, Linux distributions represented five of the top ten, FreeBSD three of ten, and Microsoft two of ten; as of February 2010, Linux distributions represented six of the top ten, FreeBSD two of ten, and Microsoft one of ten.)

File:JaguarXT5.jpg

The Oak Ridge National Laboratory's Jaguar supercomputer, as of November 2009 the world's fastest supercomputer. It uses the Cray Linux Environment as its operating system.

Linux distributions are the cornerstone of the LAMP server-software combination (Linux, Apache, MySQL, Perl/PHP/Python) which has achieved popularity among developers, and which is one of the more common platforms for website hosting.

Linux distributions have become increasingly popular on mainframes in the last decade due to pricing, compared to other mainframe operating systems. In December 2009, computer giant IBM reported that it would predominantly market and sell mainframe-based Enterprise Linux Server.

Linux distributions are also commonly used as operating systems for supercomputers: as of November 2009, out of the top 500 systems, 446 (89.2%) run a Linux distribution.

Linux was also selected as the operating system for the world's most powerful supercomputer, IBM's Sequoia which will become operational in 2011.

Embedded devices

See also: Embedded Linux and Linux devices

An HTC Dream running Android

Due to its low cost and ease of modification, an embedded Linux is often used in embedded systems. Linux has become a major competitor of Symbian OS which is used in the majority of smartphones—16.7% of smartphones sold worldwide during 2006 were using Linux—and it is an alternative to the proprietary Windows CE and Palm OS operating systems on mobile devices. Cell phones or PDAs running on Linux and built on open source platform became a trend from 2007, like Nokia N810, Openmoko's Neo1973, Motorola RAZR2 v8, Motorola ROKR E8, Motorola MING series, Motorola ZINE and Google Android. The popular TiVo digital video recorder uses a customized version of Linux. Several network firewall and router standalone products, including several from Cisco/Linksys, use Linux internally, using its advanced firewall and routing capabilities. The Korg OASYS, Roland RD-700GX and the Yamaha Motif XS music workstations also run Linux. Furthermore, Linux is used in the leading stage lighting control system, FlyingPig/HighEnd WholeHogIII Console.

Market share and uptake

Main article: Linux adoption

See also: Usage share of operating systems

Many quantitative studies of free / open source software focus on topics including market share and reliability, with numerous studies specifically examining Linux. The Linux market is growing rapidly, and the revenue of servers, desktops, and packaged software running Linux was expected to exceed $35.7 billion by 2008.

IDC's Q1 2007 report indicated that Linux held 12.7% of the overall server market at that time. This estimate was based on the number of Linux servers sold by various companies and did not include server hardware purchased separately and had Linux installed on it later. In September 2008 Microsoft CEO Steve Ballmer admitted that 60% of web-servers run Linux versus 40% that run Windows Server.

Companies have, mostly based on web server statistics, estimated that the desktop market share of Linux range from less than 1% to 2.14%. In comparison, Microsoft operating systems hold more than 85%.

The frictional cost of switching operating systems, lack of support for certain hardware and application programs designed for Microsoft Windows, and work by Microsoft to actively prevent large-scale installations have been three factors that have inhibited adoption. Proponents and analysts attribute the relative success of Linux to its security, reliability, low cost, and freedom from vendor lock-in.

Also most recently Google has begun to fund Wine, which acts as a compatibility layer, allowing users to run some Windows programs under Linux.

The XO laptop project of One Laptop Per Child is creating a new and potentially much larger Linux community, planned to reach millions of schoolchildren and their families and communities in developing countries. Google, Red Hat, and eBay are major supporters of the project. While the XO will also have a Windows option, it will be primarily deployed using Sugar, a desktop environment for Fedora Linux.

In the film industry, Linux has been the platform of choice for several years. The first major film produced on Linux servers was Titanic in 1997. Since then major studios like Dreamworks Animation, Pixar and Industrial Light & Magic have moved to Linux. According to the Linux Movies Group, more than 95% of the servers and desktops at large animation and visual effects companies use Linux.

Copyright and naming

See also: SCO-Linux controversies

The Linux and most GNU software are licensed under the GNU General Public License (GPL). The GPL requires that anyone who distributes the Linux must make the source code (and any modifications) available to the recipient under the same terms. Other key components of a software system may use other licenses; many libraries use the GNU Lesser General Public License (LGPL), a more permissive variant of the GPL, and the X Window System uses the MIT License.

Torvalds states that the Linux will not move from version 2 of the GPL to version 3. He specifically dislikes some provisions in the new license which prohibit the use of the software in digital rights management, and it would also be impractical to obtain permission from all the copyright holders, who number in the thousands.

A 2001 study of Red Hat Linux 7.1 found that this distribution contained 30 million source lines of code. Using the Constructive Cost Model, the study estimated that this distribution required about eight thousand man-years of development time. According to the study, if all this software had been developed by conventional proprietary means, it would have cost about $1.91 billion (2025 US dollars) to develop in the United States.

Most of the code (71%) was written in the C programming language, but many other languages were used, including C++, assembly language, Perl, Python, Fortran, and various shell scripting languages. Slightly over half of all lines of code were licensed under the GPL. The Linux kernel itself was 2.4 million lines of code, or 8% of the total.

In a later study, the same analysis was performed for Debian GNU/Linux version 4.0 (etch, which was released in 2007). This distribution contained close to 283 million source lines of code, and the study estimated that it would have cost $10.5 billion (2025 US dollars) to develop by conventional means.

In the United States, the name Linux is a trademark registered to Linus Torvalds. Initially, nobody registered it, but on 15 August 1994, William R. Della Croce, Jr. filed for the trademark Linux, and then demanded royalties from Linux distributors. In 1996, Torvalds and some affected organizations sued him to have the trademark assigned to Torvalds, and in 1997 the case was settled. The licensing of the trademark has since been handled by the Linux Mark Institute. Torvalds has stated that he trademarked the name only to prevent someone else from using it. LMI originally charged a nominal sublicensing fee for use of the Linux name as part of trademarks, but later changed this in favor of offering a free, perpetual worldwide sublicense.

GNU/Linux

Main article: GNU/Linux naming controversy

The Free Software Foundation views Linux distributions which use GNU software as GNU variants and they ask that such operating systems be referred to as GNU/Linux or a Linux-based GNU system. The media and common usage, however, refers to this family of operating systems simply as Linux, as do many large Linux distributions (e.g. Ubuntu, SuSE Linux or Mandriva Linux). Some distributions use GNU/Linux (particularly notable is Debian GNU/Linux, on which Ubuntu is based), but the term's use outside of the enthusiast community is limited. The naming issue remains controversial.

See also

• The Cathedral and the Bazaar
• Comparison of Linux distributions
• Comparison of operating systems
• Comparison of Windows and Linux
• Comparison of Windows versions
• List of operating systems
• Market share of operating systems
• Comparison of open source and closed source

Further reading

• Weinberg, Bill (July 2008). Uniting Mobile Linux Application Platforms (PDF). LinuxPundit.com. p. 18.

External links

• Template:Dmoz
• GNU Project website
• Graphical map of GNU/Linux OS Internals
• Linux.com website
• Linux Documentation Project
• Linux Foundation
• Linux kernel website and archives
• Linux Mark Institute (manages the Linux trade mark)
• Linux.org website

"GNU/Linux" redirects here. For the "GNU" part, see GNU/Linux naming controversy.

Linux

Developer	Linus Torvalds and thousands of collaborators
Written in	C
OS family	Unix-like
Working state	Current
Source model	Free and open source software
Marketing target	Desktops, servers, embedded devices
Available in	Multi-lingual
Platforms	IA-32, MIPS, x86-64, SPARC, DEC Alpha, Itanium, PowerPC, ARM, m68k, PA-RISC, s390, SuperH, M32R and more
Kernel type	Monolithic
Userland	GNU and others
Default user interface	Graphical (X Window System)
License	Various including GNU General Public License, BSD License, Apache License, MIT License, and others
Official website	www.kernel.org

Linux (commonly Template:Pron-en LIN-əks in American English, also Template:Pron-en LIN-ooks in Europe and Canada) is a generic term referring to Unix-like computer operating systems that use the Linux kernel. Their development is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified, and redistributed, both commercially and non-commercially, by anyone under licenses such as the GNU General Public License.

Linux can be installed on a wide variety of computer hardware, ranging from embedded devices such as mobile phones, smartphones and wristwatches to mainframes and supercomputers. Linux is predominantly known for its use in servers; in 2007 Linux's overall share of the server market was estimated at 12.7%, while a 2008 estimate suggested that 60% of all web servers ran Linux. Most desktop computers run either Mac OS X or Microsoft Windows, with Linux having only 1–2% of the desktop market. However, desktop use of Linux has become increasingly popular in recent years, partly owing to the popular Mandriva Linux, Fedora, Debian or Ubuntu distributions and the emergence of netbooks and smartbooks.

Typically Linux is packaged in a format known as a Linux distribution for desktop and server use. Linux distributions include the Linux kernel and all of the supporting software required to run a complete system, such as utilities and libraries, the X Window System, the GNOME and KDE desktop environments, and the Apache HTTP Server. Commonly-used applications with desktop Linux systems include the Mozilla Firefox web-browser, the OpenOffice.org office application suite and the GIMP image editor.

The name "Linux" comes from the Linux kernel, originally written in 1991 by Linus Torvalds. The main supporting Userland in the form of system tools and libraries from the GNU Project (announced in 1983 by Richard Stallman) is the basis for the Free Software Foundation's preferred name GNU/Linux.

History

See also: History of Linux

Unix

The Unix operating system was conceived and implemented in 1969 at AT&T's Bell Laboratories in the United States by Ken Thompson, Dennis Ritchie, Douglas McIlroy, and Joe Ossanna. Unix derived its name as a joke and reference to an experimental operating system that was slow and ineffective called MULTICS. It was first released in 1971 and was initially entirely written in assembly language, a common practice at the time. Later, in a key pioneering approach in 1973, Unix was re-written in the programming language C by Dennis Ritchie, (with exceptions to the kernel and I/O). The availability of an operating system written in a high-level language allowed easier portability to different computer platforms. With a legal glitch forcing AT&T to license the operating system's source code, Unix quickly grew and became widely adopted by academic institutions and businesses.

GNU

The GNU Project, started in 1983 by Richard Stallman, had the goal of creating a "complete Unix-compatible software system" composed entirely of free software. Work began in 1984. Later, in 1985, Stallman created the Free Software Foundation and wrote the GNU General Public License (GNU GPL) in 1989. By the early 1990s, many of the programs required in an operating system (such as libraries, compilers, text editors, a Unix shell, and a windowing system) were completed, although low-level elements such as device drivers, daemons, and the kernel were stalled and incomplete. Linus Torvalds has said that if the GNU kernel had been available at the time (1991), he would not have decided to write his own.

MINIX

Andrew S. Tanenbaum, author of the MINIX operating system

MINIX was an inexpensive minimal Unix-like operating system, designed for education in computer science, written by Andrew S. Tanenbaum. As of version 3, MINIX is free and redesigned also for “serious” use.

In 1991 while attending the University of Helsinki, Torvalds, curious about the operating systems and frustrated by the licensing of MINIX limiting it to educational use only (which prevented any commercial use) began to work on his own operating system which eventually became Linux.

Torvalds began the development of Linux on MINIX and applications written for MINIX were also used on Linux. Later Linux matured and it became possible for Linux to be developed under itself. Also GNU applications replaced all MINIX ones because, with code from the GNU system freely available, it was advantageous if this could be used with the fledgling operating system. Code licensed under the GNU GPL can be used in other projects, so long as they also are released under the same or a compatible license. In order to make the Linux available for commercial use, Torvalds initiated a switch from his original license (which prohibited commercial redistribution) to the GNU GPL. Developers worked to integrate GNU components with Linux to make a fully functional and free operating system.

Commercial and popular uptake

Main article: Linux adoption

Today Linux distributions are used in numerous domains, from embedded systems to supercomputers, and have secured a place in server installations with the popular LAMP application stack. Use of Linux distributions in home and enterprise desktops has been expanding. They have also gained popularity with various local and national governments. The federal government of Brazil is well known for its support for Linux. News of the Russian military creating their own Linux distribution has also surfaced, and has come to fruition as the G.H.ost Project. The Indian state of Kerala has gone so far as to make it mandatory for all state high schools to run Linux on their computers. China uses Linux exclusively as the operating system for its Loongson processor family to achieve technology independence. In Spain some regions have developed their own Linux distributions, which are widely used in education and official institutions, like gnuLinEx in Extremadura and Guadalinex in Andalusia. France and Germany have also taken steps towards the adoption of Linux.

Linux distributions have also become popular with the newly founded netbook market, with many devices such as the ASUS Eee PC and Acer Aspire One shipping with customized Linux distributions installed.

Current development

Torvalds continues to direct the development of the kernel. Stallman heads the Free Software Foundation, which in turn supports the GNU components. Finally, individuals and corporations develop third-party non-GNU components. These third-party components comprise a vast body of work and may include both kernel modules and user applications and libraries. Linux vendors and communities combine and distribute the kernel, GNU components, and non-GNU components, with additional package management software in the form of Linux distributions.

Design

A Linux-based system is a modular Unix-like operating system. It derives much of its basic design from principles established in Unix during the 1970s and 1980s. Such a system uses a monolithic kernel, the Linux kernel, which handles process control, networking, and peripheral and file system access. Device drivers are either integrated directly with the kernel or added as modules loaded while the system is running.

Separate projects that interface with the kernel provide much of the system's higher-level functionality. The GNU userland is an important part of most Linux-based systems, providing the most common implementation of the C library, a popular shell, and many of the common Unix tools which carry out many basic operating system tasks. The graphical user interface (or GUI) used by most Linux systems is built on top of an implementation of the X Window System.

User interface

See also: User interface

Users can control a Linux-based system through a command line interface (or CLI), a graphical user interface (or GUI), or through controls attached to the associated hardware (this is common for embedded systems). For desktop systems, the default mode is usually graphical user interface, where the CLI is available through terminal emulator windows or on a separate virtual console.

On desktop machines, KDE, GNOME, and Xfce are the most popular user interfaces, though a variety of additional user interfaces exist. Most popular user interfaces run on top of the X Window System (often simply called "X"), which provides network transparency, enabling a graphical application running on one machine to be displayed and controlled from another.

Other GUIs include X window managers such as FVWM, Enlightenment, and Window Maker. The window manager provides a means to control the placement and appearance of individual application windows, and interacts with the X Window System. This is a more minimalist goal than KDE, GNOME et al., which are termed desktop environments.

A Linux system typically provides a CLI through a shell, which is the traditional way of interacting with a Unix system. A Linux distribution specialized for servers may use the CLI as its only interface.

Most low-level Linux components, including the GNU userland, use the CLI exclusively. The CLI is particularly suited for automation of repetitive or delayed tasks, and provides very simple inter-process communication. A graphical terminal emulator program is often used to access the CLI from a Linux desktop.

Development

A summarized history of Unix-like operating systems showing Linux's origins. Note that despite similar architectural designs and concepts being shared as part of the POSIX standard, Linux does not share any non-free source code with the original Unix or MINIX.

Main article: Linux distribution

The primary difference between Linux and many other popular contemporary operating systems is that the Linux kernel and other components are free and open source software. Linux is not the only such operating system, although it is by far the most widely used. Some free and open source software licenses are based on the principle of copyleft, a kind of reciprocity: any work derived from a copyleft piece of software must also be copyleft itself. The most common free software license, the GNU GPL, is a form of copyleft, and is used for the Linux kernel and many of the components from the GNU project.

Linux based distributions are intended by developers for interoperability with other operating systems and established computing standards. Linux systems adhere to POSIX, SUS, ISO, and ANSI standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT.

Free software projects, although developed in a collaborative fashion, are often produced independently of each other. The fact that the software licenses explicitly permit redistribution, however, provides a basis for larger scale projects that collect the software produced by stand-alone projects and make it available all at once in the form of a Linux distribution.

A Linux distribution, commonly called a "distro", is a project that manages a remote collection of system software and application software packages available for download and installation through a network connection. This allows the user to adapt the operating system to his/her specific needs. Distributions are maintained by individuals, loose-knit teams, volunteer organizations, and commercial entities. A distribution is responsible for the default configuration of the installed Linux kernel, general system security, and more generally integration of the different software packages into a coherent whole. Distributions typically use a package manager such as Synaptic, YAST, or Portage to install, remove and update all of a system's software from one central location.

Community

See also: Free software community and Linux Users Group

A distribution is largely driven by its developer and user communities. Some vendors develop and fund their distributions on a volunteer basis, Debian being a well-known example. Others maintain a community version of their commercial distributions, as Red Hat does with Fedora.

In many cities and regions, local associations known as Linux Users Groups (LUGs) seek to promote their preferred distribution and by extension free software. They hold meetings and provide free demonstrations, training, technical support, and operating system installation to new users. Many Internet communities also provide support to Linux users and developers. Most distributions and free software / open source projects have IRC chatrooms or newsgroups. Online forums are another means for support, with notable examples being LinuxQuestions.org and the Gentoo forums. Linux distributions host mailing lists; commonly there will be a specific topic such as usage or development for a given list.

There are several technology websites with a Linux focus. Print magazines on Linux often include cover disks including software or even complete Linux distributions.

Although Linux distributions are generally available without charge, several large corporations sell, support, and contribute to the development of the components of the system and of free software. An analysis of Linux showed 75 percent of the code from December 2008 to January 2010 was developed by programmers working for corporations, leaving about 18 percent to the traditional, open source community. Some of the major corporations that contribute include Dell, IBM, HP, Oracle, Sun Microsystems, Novell, Nokia. A number of corporations, notably Red Hat, have built their entire business around Linux distributions.

The free software licenses, on which the various software packages of a distribution built on the Linux kernel are based, explicitly accommodate and encourage commercialization; the relationship between a Linux distribution as a whole and individual vendors may be seen as symbiotic. One common business model of commercial suppliers is charging for support, especially for business users. A number of companies also offer a specialized business version of their distribution, which adds proprietary support packages and tools to administer higher numbers of installations or to simplify administrative tasks. Another business model is to give away the software in order to sell hardware.

Programming on Linux

Most Linux distributions support dozens of programming languages. The most common collection of utilities for building both Linux applications and operating system programs is found within the GNU toolchain, which includes the GNU Compiler Collection (GCC) and the GNU build system. Amongst others, GCC provides compilers for Ada, C, C++, Java, and Fortran. The Linux kernel itself is written to be compiled with GCC. Proprietary compilers for Linux include the Intel C++ Compiler, Sun Studio, and IBM XL C/C++ Compiler. BASIC is supported in such forms as Gambas, FreeBASIC, and XBasic.

Most distributions also include support for PHP, Perl, Ruby, Python and other dynamic languages. While not as common, Linux also supports C# via the Mono project, sponsored by Novell, and Scheme. A number of Java Virtual Machines and development kits run on Linux, including the original Sun Microsystems JVM (HotSpot), and IBM's J2SE RE, as well as many open-source projects like Kaffe.

The two main frameworks for developing graphical applications are those of GNOME and KDE. These projects are based on the GTK+ and Qt widget toolkits, respectively, which can also be used independently of the larger framework. Both support a wide variety of languages. There are a number of Integrated development environments available including Anjuta, Code::Blocks, Eclipse, KDevelop, Lazarus, MonoDevelop, NetBeans, Qt Creator and Omnis Studio while the long-established editors Vim and Emacs remain popular.

Uses

As well as those designed for general purpose use on desktops and servers, distributions may be specialized for different purposes including: computer architecture support, embedded systems, stability, security, localization to a specific region or language, targeting of specific user groups, support for real-time applications, or commitment to a given desktop environment. Furthermore, some distributions deliberately include only free software. Currently, over three hundred distributions are actively developed, with about a dozen distributions being most popular for general-purpose use.

Linux is a widely ported operating system kernel. The Linux kernel runs on a highly diverse range of computer architectures: in the hand-held ARM-based iPAQ and the mainframe IBM System z9, System z10 in devices ranging from mobile phones to supercomputers. Specialized distributions exist for less mainstream architectures. The ELKS kernel fork can run on Intel 8086 or Intel 80286 16-bit microprocessors, while the µClinux kernel fork may run on systems without a memory management unit. The kernel also runs on architectures that were only ever intended to use a manufacturer-created operating system, such as Macintosh computers (with both PowerPC and Intel processors), PDAs, video game consoles, portable music players, and mobile phones.

There are several industry associations and hardware conferences devoted to maintaining and improving support for diverse hardware under Linux, such as FreedomHEC.

Desktop

GNOME

KDE

Xfce

LXDE

Main article: Desktop Linux

The popularity of Linux on standard desktops (and laptops) has been increasing over the years. Currently most distributions include a graphical user environment. The two most popular such environments are GNOME and KDE, both of which are mature and support a wide variety of languages.

The performance of Linux on the desktop has been a controversial topic; for example in 2007 Con Kolivas accused the Linux community of favoring performance on servers. He quit Linux kernel development because he was frustrated with this lack of focus on the desktop, and then gave a "tell all" interview on the topic. Since then a significant effort has been expended improving the desktop experience. Projects such as upstart aim for a faster boot time. In the field of gaming, the Linux desktop still lags behind Windows. However, there are several companies that do port their own or other companies' games to Linux.

Many types of applications available for Microsoft Windows and Mac OS X are also available for Linux. Commonly, either a free software application will exist which does the functions of an application found on another operating systems, or that application will have a version that works on Linux (such as Skype). Furthermore, the Wine project provides a Windows compatibility layer to run unmodified Windows applications on Linux. CrossOver is a proprietary solution based on the open source Wine project that supports running Windows versions of Microsoft Office, Intuit applications such as Quicken and QuickBooks, Adobe Photoshop versions through CS2, and many popular games such as World of Warcraft and Team Fortress 2. In other cases, where there is no Linux port of some software in areas such as desktop publishing and professional audio, there is equivalent software available on Linux.

Many popular applications are available for a wide variety of operating systems. For example Mozilla Firefox, and OpenOffice.org have downloadable versions for all major operating systems. Furthermore, some applications were initially developed for Linux (such as Pidgin, and GIMP) and, due to their popularity, were ported to other operating systems (including Windows and Mac OS X).

A growing number of proprietary desktop applications are also supported on Linux, see List of proprietary software for Linux. In the field of animation and visual effects, most high end software, such as AutoDesk Maya, Softimage XSI and Apple Shake, is available for Linux, Windows and/or Mac OS X.

The collaborative nature of free software development allows distributed teams to localize Linux distributions for use in locales where localizing proprietary systems would not be cost-effective. For example the Sinhalese language version of the Knoppix distribution was available significantly before Microsoft Windows XP was translated to Sinhalese. In this case the Lanka Linux User Group played a major part in developing the localized system by combining the knowledge of university professors, linguists, and local developers.

Installing new software in Linux is typically done through the use of package managers such as Synaptic Package Manager, PackageKit, and Yum Extender. While major Linux distributions have extensive repositories (tens of thousands of packages), not all the software that can run on Linux is available from the official repositories. Alternatively, users can install packages from unofficial repositories, download pre-compiled packages directly from websites, or compile the source code by themselves. All these methods come with different degrees of difficulty, compiling the source code is in general considered a challenging process for new Linux users, but it's hardly needed in modern distributions.

Servers, mainframes and supercomputers

Servers designed for Linux

Linux distributions have long been used as server operating systems, and have risen to prominence in that area; Netcraft reported in September 2006 that eight of the ten most reliable internet hosting companies ran Linux distributions on their web servers. (As of June 2008, Linux distributions represented five of the top ten, FreeBSD three of ten, and Microsoft two of ten; as of February 2010, Linux distributions represented six of the top ten, FreeBSD two of ten, and Microsoft one of ten.)

File:JaguarXT5.jpg

The Oak Ridge National Laboratory's Jaguar supercomputer, as of November 2009 the world's fastest supercomputer. It uses the Cray Linux Environment as its operating system.

Linux distributions are the cornerstone of the LAMP server-software combination (Linux, Apache, MySQL, Perl/PHP/Python) which has achieved popularity among developers, and which is one of the more common platforms for website hosting.

Linux distributions have become increasingly popular on mainframes in the last decade due to pricing, compared to other mainframe operating systems. In December 2009, computer giant IBM reported that it would predominantly market and sell mainframe-based Enterprise Linux Server.

Linux distributions are also commonly used as operating systems for supercomputers: as of November 2009, out of the top 500 systems, 446 (89.2%) run a Linux distribution.

Linux was also selected as the operating system for the world's most powerful supercomputer, IBM's Sequoia which will become operational in 2011.

Embedded devices

See also: Embedded Linux and Linux devices

An HTC Dream running Android

Due to its low cost and ease of modification, an embedded Linux is often used in embedded systems. Linux has become a major competitor of Symbian OS which is used in the majority of smartphones—16.7% of smartphones sold worldwide during 2006 were using Linux—and it is an alternative to the proprietary Windows CE and Palm OS operating systems on mobile devices. Cell phones or PDAs running on Linux and built on open source platform became a trend from 2007, like Nokia N810, Openmoko's Neo1973, Motorola RAZR2 v8, Motorola ROKR E8, Motorola MING series, Motorola ZINE and Google Android. The popular TiVo digital video recorder uses a customized version of Linux. Several network firewall and router standalone products, including several from Cisco/Linksys, use Linux internally, using its advanced firewall and routing capabilities. The Korg OASYS, Roland RD-700GX and the Yamaha Motif XS music workstations also run Linux. Furthermore, Linux is used in the leading stage lighting control system, FlyingPig/HighEnd WholeHogIII Console.

Market share and uptake

Main article: Linux adoption

See also: Usage share of operating systems

Many quantitative studies of free / open source software focus on topics including market share and reliability, with numerous studies specifically examining Linux. The Linux market is growing rapidly, and the revenue of servers, desktops, and packaged software running Linux was expected to exceed $35.7 billion by 2008.

IDC's Q1 2007 report indicated that Linux held 12.7% of the overall server market at that time. This estimate was based on the number of Linux servers sold by various companies and did not include server hardware purchased separately and had Linux installed on it later. In September 2008 Microsoft CEO Steve Ballmer admitted that 60% of web-servers run Linux versus 40% that run Windows Server.

Companies have, mostly based on web server statistics, estimated that the desktop market share of Linux range from less than 1% to 2.14%. In comparison, Microsoft operating systems hold more than 85%.

The frictional cost of switching operating systems, lack of support for certain hardware and application programs designed for Microsoft Windows, and work by Microsoft to actively prevent large-scale installations have been three factors that have inhibited adoption. Proponents and analysts attribute the relative success of Linux to its security, reliability, low cost, and freedom from vendor lock-in.

Also most recently Google has begun to fund Wine, which acts as a compatibility layer, allowing users to run some Windows programs under Linux.

The XO laptop project of One Laptop Per Child is creating a new and potentially much larger Linux community, planned to reach millions of schoolchildren and their families and communities in developing countries. Google, Red Hat, and eBay are major supporters of the project. While the XO will also have a Windows option, it will be primarily deployed using Sugar, a desktop environment for Fedora Linux.

In the film industry, Linux has been the platform of choice for several years. The first major film produced on Linux servers was Titanic in 1997. Since then major studios like Dreamworks Animation, Pixar and Industrial Light & Magic have moved to Linux. According to the Linux Movies Group, more than 95% of the servers and desktops at large animation and visual effects companies use Linux.

Copyright and naming

See also: SCO-Linux controversies

The Linux and most GNU software are licensed under the GNU General Public License (GPL). The GPL requires that anyone who distributes the Linux must make the source code (and any modifications) available to the recipient under the same terms. Other key components of a software system may use other licenses; many libraries use the GNU Lesser General Public License (LGPL), a more permissive variant of the GPL, and the X Window System uses the MIT License.

Torvalds states that the Linux will not move from version 2 of the GPL to version 3. He specifically dislikes some provisions in the new license which prohibit the use of the software in digital rights management, and it would also be impractical to obtain permission from all the copyright holders, who number in the thousands.

A 2001 study of Red Hat Linux 7.1 found that this distribution contained 30 million source lines of code. Using the Constructive Cost Model, the study estimated that this distribution required about eight thousand man-years of development time. According to the study, if all this software had been developed by conventional proprietary means, it would have cost about $1.91 billion (2025 US dollars) to develop in the United States.

Most of the code (71%) was written in the C programming language, but many other languages were used, including C++, assembly language, Perl, Python, Fortran, and various shell scripting languages. Slightly over half of all lines of code were licensed under the GPL. The Linux kernel itself was 2.4 million lines of code, or 8% of the total.

In a later study, the same analysis was performed for Debian GNU/Linux version 4.0 (etch, which was released in 2007). This distribution contained close to 283 million source lines of code, and the study estimated that it would have cost $10.5 billion (2025 US dollars) to develop by conventional means.

In the United States, the name Linux is a trademark registered to Linus Torvalds. Initially, nobody registered it, but on 15 August 1994, William R. Della Croce, Jr. filed for the trademark Linux, and then demanded royalties from Linux distributors. In 1996, Torvalds and some affected organizations sued him to have the trademark assigned to Torvalds, and in 1997 the case was settled. The licensing of the trademark has since been handled by the Linux Mark Institute. Torvalds has stated that he trademarked the name only to prevent someone else from using it. LMI originally charged a nominal sublicensing fee for use of the Linux name as part of trademarks, but later changed this in favor of offering a free, perpetual worldwide sublicense.

GNU/Linux

Main article: GNU/Linux naming controversy

The Free Software Foundation views Linux distributions which use GNU software as GNU variants and they ask that such operating systems be referred to as GNU/Linux or a Linux-based GNU system. The media and common usage, however, refers to this family of operating systems simply as Linux, as do many large Linux distributions (e.g. Ubuntu, SuSE Linux or Mandriva Linux). Some distributions use GNU/Linux (particularly notable is Debian GNU/Linux, on which Ubuntu is based), but the term's use outside of the enthusiast community is limited. The naming issue remains controversial.

See also

• The Cathedral and the Bazaar
• Comparison of Linux distributions
• Comparison of operating systems
• Comparison of Windows and Linux
• Comparison of Windows versions
• List of operating systems
• Market share of operating systems
• Comparison of open source and closed source

Further reading

• Weinberg, Bill (July 2008). Uniting Mobile Linux Application Platforms (PDF). LinuxPundit.com. p. 18.

External links

• Template:Dmoz
• GNU Project website
• Graphical map of GNU/Linux OS Internals
• Linux.com website
• Linux Documentation Project
• Linux Foundation
• Linux kernel website and archives
• Linux Mark Institute (manages the Linux trade mark)
• Linux.org website

Windows 7

File:Windows 7.png Screenshot of Windows 7 Ultimate
Developer	Microsoft
OS family	Microsoft Windows
Source model	Closed source / Shared source
Released to manufacturing	RTM: July 22, 2009 Retail: October 22, 2009
Latest release	6.1 (build 7600.16385.090713-1255) / October 22, 2009 (2009-10-22)
Update method	Windows Update
Platforms	IA-32, x86-64
Kernel type	Hybrid
License	MS-EULA
Official website	Official website
Support status
Mainstream support
Articles in the series
Development of Windows 7 Features new to Windows 7 List of features removed in Windows 7 Windows 7 editions

Windows 7 is a version of Microsoft Windows, a series of operating systems produced by Microsoft for use on personal computers, including home and business desktops, laptops, netbooks, tablet PCs, and media center PCs. Windows 7 was released to manufacturing on July 22, 2009, and reached general retail availability on October 22, 2009, less than three years after the release of its predecessor, Windows Vista. Windows 7's server counterpart, Windows Server 2008 R2, was released at the same time. Windows 7 will be succeeded by Windows 8, which has no release date as of yet.

Unlike its predecessor, which introduced a large number of new features, Windows 7 was intended to be a more focused, incremental upgrade to the Windows line, with the goal of being compatible with applications and hardware with which Windows Vista is already compatible. Presentations given by Microsoft in 2008 focused on multi-touch support, a redesigned Windows Shell with a new taskbar, referred to as the Superbar, a home networking system called HomeGroup, and performance improvements. Some applications that have been included with prior releases of Microsoft Windows, including Windows Calendar, Windows Mail, Windows Movie Maker, and Windows Photo Gallery, are not included in Windows 7; most are instead offered separately at no charge as part of the Windows Live Essentials suite.

Development

Main article: Development of Windows 7

Originally, a version of Windows codenamed Blackcomb was planned as the successor to Windows XP (codename Whistler) and Windows Server 2003. Major features were planned for Blackcomb, including an emphasis on searching and querying data and an advanced storage system named WinFS to enable such scenarios. However, an interim, minor release, codenamed "Longhorn," was announced for 2003, delaying the development of Blackcomb. By the middle of 2003, however, Longhorn had acquired some of the features originally intended for Blackcomb. After three major viruses exploited flaws in Windows operating systems within a short time period in 2003, Microsoft changed its development priorities, putting some of Longhorn's major development work on hold while developing new service packs for Windows XP and Windows Server 2003. Development of Longhorn (Windows Vista) was also restarted, and thus delayed, in August 2004. A number of features were cut from Longhorn. Windows 7 is programmed in C, C++, and Assembly.

Blackcomb was renamed Vienna in early 2006 and again Windows 7 in 2007. In 2008, it was announced that Windows 7 would also be the official name of the operating system. There has been some confusion over naming the product Windows 7, while versioning it as 6.1 to indicate its similar build to Vista and increase compatibility with applications that only check major version numbers, similar to Windows 2000 and Windows XP both having 5.x version numbers.

The first external release to select Microsoft partners came in January 2008 with Milestone 1, build 6519. At PDC 2008, Microsoft demonstrated Windows 7 with its reworked taskbar. Copies of Windows 7 build 6801 were distributed at the end of the conference; however, the demonstrated taskbar was disabled in this build.

On December 27, 2008, Windows 7 Beta was leaked onto the Internet via BitTorrent. According to a performance test by ZDNet, Windows 7 Beta beat both Windows XP and Vista in several key areas; including boot and shutdown time and working with files, such as loading documents. Other areas did not beat XP; including PC Pro benchmarks for typical office activities and video editing, which remain identical to Vista and slower than XP. On January 7, 2009, the 64-bit version of the Windows 7 Beta (build 7000) was leaked onto the web, with some torrents being infected with a trojan. At CES 2009, Microsoft CEO Steve Ballmer announced the Windows 7 Beta, build 7000, had been made available for download to MSDN and TechNet subscribers in the format of an ISO image. The Beta was to be publicly released January 9, 2009, and Microsoft initially planned for the download to be made available to 2.5 million people on this date. However, access to the downloads was delayed because of high traffic. The download limit was also extended, initially until January 24, then again to February 10. People who did not complete downloading the beta had two extra days to complete the download. After February 12, unfinished downloads became unable to complete. Users could still obtain product keys from Microsoft to activate their copies of Windows 7 Beta, which expired on August 1, 2009. The release candidate, build 7100, has been available for MSDN and TechNet subscribers and Connect Program participants since April 30 and became available to the general public on May 5, 2009. It has also been leaked onto the Internet via BitTorrent. The release candidate is available in five languages and will expire on June 1, 2010, with shutdowns every two hours starting March 1, 2010. Microsoft stated that Windows 7 would be released to the general public on October 22, 2009. Microsoft released Windows 7 to MSDN and Technet subscribers on August 6, 2009, at 10:00 a.m. PDT. Microsoft announced that Windows 7, along with Windows Server 2008 R2, was released to manufacturing on July 22, 2009. Windows 7 RTM is build 7600.16385, which was compiled on July 13, 2009, and was declared the final RTM build after passing all Microsoft's tests internally.

Goals

Bill Gates, in an interview with Newsweek, suggested that this version of Windows would be more "user-centric". Gates later said that Windows 7 would also focus on performance improvements. Steven Sinofsky later expanded on this point, explaining in the Engineering Windows 7 blog that the company was using a variety of new tracing tools to measure the performance of many areas of the operating system on an ongoing basis, to help locate inefficient code paths and to help prevent performance regressions.

Senior Vice President Bill Veghte stated that Windows Vista users migrating to Windows 7 would not find the kind of device compatibility issues they encountered migrating from Windows XP. Speaking about Windows 7 on October 16, 2008, Microsoft CEO Steve Ballmer confirmed compatibility between Vista and Windows 7, indicating that Windows 7 would be a refined version of Windows Vista.

Features

New and changed features

Main article: Features new to Windows 7

The new Action Center, which replaces Windows Security Center

When the action center detects a security threat, it displays a thumbnail with problems listed.

Windows 7 includes a number of new features, such as advances in touch and handwriting recognition, support for virtual hard disks, improved performance on multi-core processors, improved boot performance, DirectAccess, and kernel improvements. Windows 7 adds support for systems using multiple heterogeneous graphics cards from different vendors (Heterogeneous Multi-adapter), a new version of Windows Media Center, a Gadget for Windows Media Center, improved media features, the XPS Essentials Pack and Windows PowerShell being included, and a redesigned Calculator with multiline capabilities including Programmer and Statistics modes along with unit conversion. Many new items have been added to the Control Panel, including ClearType Text Tuner, Display Color Calibration Wizard, Gadgets, Recovery, Troubleshooting, Workspaces Center, Location and Other Sensors, Credential Manager, Biometric Devices, System Icons, and Display. Windows Security Center has been renamed to Windows Action Center (Windows Health Center and Windows Solution Center in earlier builds), which encompasses both security and maintenance of the computer. The default setting for User Account Control in Windows 7 has been criticized for allowing untrusted software to be launched with elevated privileges by exploiting a trusted application. Microsoft's Windows kernel engineer Mark Russinovich acknowledged the problem, but noted that there are other vulnerabilities that do not rely on the new setting. Windows 7 also supports Mac-like RAW image viewing through the addition of WIC-enabled image decoders, which enables raw image thumbnails, previewing and metadata display in Windows Explorer, plus full-size viewing and slideshows in Windows Photo Viewer and Window Media Center.

The taskbar has seen the biggest visual changes, where the Quick Launch toolbar has been replaced with pinning applications to the taskbar. Buttons for pinned applications are integrated with the task buttons. These buttons also enable the Jump Lists feature to allow easy access to common tasks. The revamped taskbar also allows the reordering of taskbar buttons. To the far right of the system clock is a small rectangular button that serves as the Show desktop icon. This button is part of the new feature in Windows 7 called Aero Peek. Hovering over this button makes all visible windows transparent for a quick look at the desktop. In touch-enabled displays such as touch screens, tablet PCs, etc., this button is slightly wider to accommodate being pressed with a finger. Clicking this button minimizes all windows, and clicking it a second time restores them. Additionally, there is a feature named Aero Snap, that automatically maximizes a window when it is dragged to either the top or left/right edges of the screen, similar to Linux. This also allows users to snap documents or files on either side of the screen to compare them. When a user moves windows that are maximized, the system restores their previous state automatically. This functionality is also accomplished with keyboard shortcuts. Unlike in Windows Vista, window borders and the taskbar do not turn opaque when a window is maximized with Windows Aero applied. Instead, they remain translucent.

The Windows 7 taskbar.

For developers, Windows 7 includes a new networking API with support for building SOAP-based web services in native code (as opposed to .NET-based WCF web services), new features to shorten application install times, reduced UAC prompts, simplified development of installation packages, and improved globalization support through a new Extended Linguistic Services API. At WinHEC 2008 Microsoft announced that color depths of 30-bit and 48-bit would be supported in Windows 7 along with the wide color gamut scRGB (which for HDMI 1.3 can be converted and output as xvYCC). The video modes supported in Windows 7 are 16-bit sRGB, 24-bit sRGB, 30-bit sRGB, 30-bit with extended color gamut sRGB, and 48-bit scRGB. Microsoft has also implemented better support for solid-state drives, including the new TRIM command, and Windows 7 is able to identify a solid-state drive uniquely. Microsoft is planning to support USB 3.0 in a subsequent patch, support not being included in the initial release due to delays in the finalization of the standard.

Internet Spades, Internet Backgammon and Internet Checkers, which were removed from Windows Vista, were restored in Windows 7. Windows 7 includes Internet Explorer 8 and Windows Media Player 12.

Users are also able to disable many more Windows components than was possible in Windows Vista. New additions to this list of components include Internet Explorer, Windows Media Player, Windows Media Center, Windows Search, and the Windows Gadget Platform. Windows 7 includes 13 additional sound schemes, titled Afternoon, Calligraphy, Characters, Cityscape, Delta, Festival, Garden, Heritage, Landscape, Quirky, Raga, Savanna, and Sonata. A new version of Microsoft Virtual PC, newly renamed as Windows Virtual PC was made available for Windows 7 Professional, Enterprise, and Ultimate editions. It allows multiple Windows environments, including Windows XP Mode, to run on the same machine. Windows XP Mode runs Windows XP in a virtual machine and redirects displayed applications running in Windows XP to the Windows 7 desktop. Furthermore, Windows 7 supports the mounting of a virtual hard disk (VHD) as a normal data storage, and the bootloader delivered with Windows 7 can boot the Windows system from a VHD, only in the Professional and Ultimate editions however. The Remote Desktop Protocol (RDP) of Windows 7 is also enhanced to support real-time multimedia application including video playback and 3D games, thus allowing use of DirectX 10 in remote desktop environments. The three application limit, previously present in the Windows Vista Starter Edition, has been removed from Windows 7.

Removed features

Main article: List of features removed in Windows 7

A number of capabilities and certain programs that were a part of Windows Vista are no longer present or have been changed, resulting in the removal of certain functionality. These include the classic Start Menu user interface, some taskbar features, Windows Explorer features, Windows Media Player features, Windows Ultimate Extras and InkBall. Four applications bundled with Windows Vista — Windows Photo Gallery, Windows Movie Maker, Windows Calendar and Windows Mail — are not included with Windows 7, but applications with mostly similar functionality are instead available for free in a separate package called Windows Live Essentials which can be found on the Microsoft website.

Antitrust regulatory attention

As with other Microsoft operating systems, Windows 7 is being studied by United States federal regulators who oversee the company's operations following the 2001 United States v. Microsoft settlement. According to status reports filed, the three-member panel began assessing prototypes of the new operating system in February 2008. Michael Gartenberg, an analyst at Jupiter Research said that, "[Microsoft's] challenge for Windows 7 will be how can they continue to add features that consumers will want that also don't run afoul of regulators."

Editions

In order to comply with European antitrust regulations, Microsoft has proposed the use of a "ballot" screen, allowing users to download a competing browser, thus removing the need for a version of Windows completely without Internet Explorer, as previously planned. In response to criticism involving Windows 7 E and concerns from manufacturers about possible consumer confusion if a version of Windows 7 with Internet Explorer were shipped later after one without Internet Explorer, Microsoft announced that it would scrap the separate version for Europe and ship the standard upgrade and full packages worldwide.

As with previous versions of Windows, an N version, which does not come with Windows Media Player, has been released in Europe, but only for sale directly from Microsoft sales websites and select others.

Reception

In July 2009, in only eight hours, pre-orders of Windows 7 at Amazon.co.uk surpassed the demand Windows Vista had in its first 17 weeks. It became the highest-grossing pre-order in Amazon's history, surpassing sales of the previous record holder, the seventh Harry Potter book. After 36 hours, 64-bit versions of Windows 7 Professional and Ultimate editions sold out in Japan. Two weeks after its release, it was announced that its market share had surpassed that of Snow Leopard, released two months previously as the most recent update to Apple's Mac OS X operating system. According to Net Applications, Windows 7 reached a 4% market share in less than three weeks. In comparison, it took Windows Vista seven months to reach the same mark. As of March 4, 2010, Microsoft announced that they had sold more than 90 million Windows 7 licenses. Windows 7 has now sold more than 100 million copies in six months, making it Microsoft's fastest selling operating system.

Reviews of Windows 7 were mostly positive, praising its usability when compared to its predecessor, Windows Vista. CNET gave Windows 7 Home Premium a rating of 4.5 out of 5 stars, stating that it "is more than what Vista should have been, [and] it's where Microsoft needed to go". PC Magazine rated it a 4 out of 5 saying that Windows 7 is a "big improvement" over Windows Vista, with fewer compatibility problems, a retooled taskbar, simpler home networking and faster start-up. Maximum PC gave Windows 7 a rating of 9 out of 10 and called Windows 7 a "massive leap forward" in usability and security, and praised the new Taskbar as "worth the price of admission alone". PC World called Windows 7 a "worthy successor" to Windows XP and said that speed benchmarks showed Windows 7 to be slightly faster than Windows Vista. PC World also named Windows 7 one of the best products of the year. In its review of Windows 7, Engadget said that Microsoft has taken a "strong step forward" with Windows 7 and reported that speed is one of Windows 7's major selling points particularly for the netbook sets. LAPTOP Magazine gave Windows 7 a rating of 4 out of 5 stars and said that Windows 7 makes computing more intuitive, offered better overall performance including a "modest to dramatic" increase in battery life on laptop computers. Techradar gave it a 5 star rating calling it the best version of Windows yet. The New York Times, USA Today, The Wall Street Journal, and The Telegraph also gave Windows 7 favorable reviews.

Some Vista Ultimate users have expressed concerns over Windows 7 pricing and upgrade options. Windows Vista Ultimate users wanting to upgrade from Windows Vista to Windows 7 must either pay $219.99 to upgrade to Windows 7 Ultimate or perform a clean install, which requires them to reinstall all of their programs.

Editions

Main article: Windows 7 editions

Windows 7 is available in six different editions, but only the Home Premium, Professional, and Ultimate editions are available for retail sale to consumers in most countries. The other editions are aimed at other markets, such as the developing world or enterprise use. Each edition of Windows 7 includes all of the capabilities and features of the edition below it. All editions support the 32-bit (IA-32) processor architecture and all editions except Starter and Home Basic support the 64-bit (x86-64) processor architecture. The installation media is the same for all the consumer editions of Windows 7 that have the same processor architecture, with the license determining the features that are activated, and license upgrades permitting the subsequent unlocking of features without re-installation of the operating system. This is the first time Microsoft has distributed 2 DVDs (1 DVD for IA-32 processor architecture, the other DVD for x86-64 processor architecture) for each edition of Windows 7 (Except for Starter and Home Basic). Users who wish to upgrade to an edition of Windows 7 with more features can then use Windows Anytime Upgrade to purchase the upgrade, and unlock the features of those editions. Some copies of Windows 7 have restrictions, in which it must be distributed, sold, or bought and activated in the geographical region (One of the geographical regions can be either: Southeast Asia; India; or Latin America and the Caribbean) specified in its front cover box.

Microsoft is offering a family pack of Windows 7 Home Premium (in select markets) that allows installation on up to three PCs. The "Family Pack" costs US$259.99 in the United States; it was available at a cost of US$149.99 for some weeks when it was first introduced.

On September 18, 2009, Microsoft said they were to offer temporary student discounts for Windows 7. The offer ran in the US and the United Kingdom, with similar schemes available in Canada, Australia, Korea, Mexico, France and Germany. Students with a valid .edu or .ac.uk email address could apply for either Windows 7 Home Premium or Professional, priced at $30 or £30. This offer has ended as of January 5.

Windows 7 is also currently available as an embedded version to developers (previously Windows Embedded 2011).

Marketing

Microsoft has marketed the whole of Windows 7 as "making your PC simpler." However, the different editions of Windows 7 have been designed and marketed toward different types of people. Out of all the different editions (Starter, Home Basic, Home Premium, Professional, Enterprise, and Ultimate), the Starter edition has been designed for netbooks, Home Basic for the developing world, Home Premium designed and marketed for normal home users, Professional for businesses, Enterprise for larger businesses and corporations, and Ultimate for enthusiasts.

Hardware requirements

File:WINDOWS 7 PC STICKER.svg

The Windows 7 sticker is affixed to most PCs that meet the minimum hardware requirements for Windows 7 purchased on or after October 22, 2009

Microsoft has published the minimum specifications for a system to run Windows 7. Requirements for the 32-bit version are similar to that of premium editions of Vista, but are higher for 64-bit versions. Microsoft has released an upgrade advisor that determines if a computer is compatible with Windows 7.

Minimum hardware requirements for Windows 7

Architecture	32-bit	64-bit
Processor	1 GHz 32-bit processor	1 GHz 64-bit processor
Memory (RAM)	1 GB of RAM	2 GB of RAM
Graphics Card	DirectX 9 graphics processor with WDDM driver model 1.0 (For Aero)
HDD free space	16 GB of available disk space	20 GB of available disk space
Optical drive	DVD drive (only to install from DVD/CD Media)

Additional requirements to use certain features:

• Windows XP Mode (available on Professional, Ultimate and Enterprise), requires an additional 1 GB of RAM and an additional 15 GB of available hard disk space. The requirement for a processor capable of hardware virtualization has been lifted.
• Windows Media Center (included with Home Premium, Professional, Ultimate and Enterprise), requires a TV tuner to receive and record TV.

Service packs

Windows 7 Service Pack 1 (SP1) was announced on March 18, 2010 and is currently in development, planned for release in autumn 2010. After months of speculation by analysts, Microsoft confirmed that the service pack is to be on a much smaller scale than those released for previous versions of Windows, particularly Windows Vista. Service Pack 1 is expected to contain minor updates, including all patches and hotfixes already delivered through Windows Update, and add USB 3.0 support, improvements to Bluetooth performance, and an updated Remote Desktop client implementing upcoming RemoteFX technology.

On April 7, 2010, a build of Windows 7 Service Pack 1 dated from March 27, 2010 was leaked onto torrent sites. The leaked service pack has a build number of 6.1.7601.16537.amd64fre.win7.100327-0053 and installation has been reported to be much quicker than service packs for previous versions of Windows.

See also

• Comparison of Microsoft Windows versions
• History of Microsoft Windows
• Microsoft Security Essentials

External links

• Official Windows 7 Website - Microsoft
• Windows 7 Home Website - Microsoft
• Engineering Windows 7 - MSDN Blogs
• The Windows 7 Blog for Developers
• The Windows 7 Team Blog - Windows Team Blog
• Microsoft warns 64-bit Windows 7 users to disable Aero, Microsoft warns windows 7, 64- bit version users to disable the Aero theme in order to stay away from hackers