Index

An index is a pointer that takes you to information. Traditionally indexes are found at the back of books. They complement the contents page because they give access to information by its specific name; contents pages, on the other hand, give access through broad categories. Indexes are usually organised alphabetically; contents pages are organised according to the order of pages in the book.

Indexing skills have also been applied to periodicals and databases, and web indexing is now becoming important.

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In mathematics, an index (plural indices) is a superscript or subscript to a symbol. Superscript indices are often, but not always, used to indicate powers. Subscript indices are usually used to label a set or sequence of variables.

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In computer science, an index is usualy used for expressing an nth element. Indices are usually expressed as integer.