In computer and machine-based telecommunications terminology, a character is a unit of information that roughly corresponds to a grapheme, grapheme-like unit, or symbol, such as in an alphabet or syllabary in the written form of a natural language.
Examples of characters include letters, numerical digits, and common punctuation marks (such as '.' or '-'). The concept also includes control characters, which do not correspond to symbols in a particular natural language, but rather to other bits of information used to process text in one or more languages. Examples of control characters include carriage return or tab, as well as instructions to printers or other devices that display or otherwise process text.
Characters are typically combined into strings.
Computers and communication equipment represent characters using a character encoding that assigns each character to something — an integer quantity represented by a sequence of bits, typically — that can be stored or transmitted through a network. Two examples of popular encodings are ASCII and the UTF-8 encoding for Unicode. While most character encodings map characters to numbers and/or bit sequences, Morse code instead represents characters using a series of electrical impulses of varying length.
Historically, the term character has been widely used by industry professionals to refer to an encoded character, often as defined by the programming language or API). Likewise, character set has been widely used to refer to a specific repertoire of characters that have been mapped to specific bit sequences or numerical codes. The term glyph is used to describe a particular physical appearance of a character. Many computer fonts consist of glyphs that are indexed by the numerical code of the corresponding character.
With the advent and widespread acceptance of Unicode and bit-agnostic encoding forms, , a character is increasingly being seen as a unit of information, independent of any particular visual manifestation. The ISO/IEC 10646 (Unicode) International Standard defines character, or abstract character as "a member of a set of elements used for the organisation, control, or representation of data". Unicode's definition supplements this with explanatory notes that encourage the reader to differentiate between characters, graphemes, and glyphs, among other things.
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