Electronics

Electronics are devices which manipulate electricity and electromagnetic fields for one of two purposes. The controlling or processing of information, or the creation and distribution of power. The development of electronics started with the creation of radio electronics (which was mostly interested in vacuum tubes initially), but now electronic devices perform a variety of tasks.

Before radio, of course, electricity had been used to carry information over telephone and telegraph wires. But these systems are based on the conversion of mechanical energy into electricity and back again in a process not much different from the conversion of electrical energy to light or heat. Electronic devices are based on the intricate, small-scale processing of the electrical current/voltage itself, although they often do have visual or mechanical interfaces with the external world.

Any electronic device has three basic blocks:

Sensors or Transducers - These take signals (in the form of temperature, pressure, etc.) from physical world and convert them into current/voltage signals.
Electronic Circuits - These are electronic components woven together to manipulate, interpret and transform the signals.
Actuators - These are devices that transform current/voltage signals into physical form, where they can have some real use.

Take as an example a television. It receive broadcasts though its sensor, the antenna. Circuits inside the television are designed to transform fluctuations in an electromagnetic field so they control deflection and intensity of an electron beam to light up phosphorescent dots on the monitor screen which is the interface.