Character

A character encoding consists of a code that pairs a sequence of characters from a given set with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the storage of text in computers and the transmission of text through telecommunication networks. Common examples include Morse code, which encodes letters of the Latin alphabet as series of long and short depressions of a telegraph key; and ASCII, which encodes letters, numerals, and other symbols, both as integers and as 7-bit binary versions of those integers, generally extended with an extra zero-bit to facilitate storage in 8-bit bytes (octets).

In earlier days of computing, the introduction of character sets such as ASCII (1963) and EBCDIC (1964) began the process of standardisation. The limitations of such sets soon became apparent, and a number of ad-hoc methods developed to extend them. The need to support multiple writing systems, including the CJK family of East Asian scripts, required support for a far larger number of characters and demanded a systematic approach to character encoding rather than the previous ad hoc approaches.

Simple character sets

Conventionally character set and character encoding were considered synonymous, as the same standard would specify both what characters were available and how they were to be encoded into a stream of code units (usually with a single character per code unit). For historical reasons, MIME and systems based on it use the term charset to refer to the complete system for encoding a sequence of characters into a sequence of octets.

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