ASCII

ASCII (/ˈæski/ ^ⓘ ASS-kee), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable and 33 control characters – a total of 128 code points. The set of available punctuation had significant impact on the syntax of computer languages and text markup. ASCII hugely influenced the design of character sets used by modern computers; for example, the first 128 code points of Unicode are the same as ASCII.

ASCII encodes each code-point as a value from 0 to 127 – storable as a seven-bit integer. Ninety-five code-points are printable, including digits 0 to 9, lowercase letters a to z, uppercase letters A to Z, and commonly used punctuation symbols. For example, the letter i is represented as 105 (decimal). Also, ASCII specifies 33 non-printing control codes which originated with Teletype devices; most of which are now obsolete. The control characters that are still commonly used include carriage return, line feed, and tab.

ASCII lacks code-points for characters with diacritical marks and therefore does not directly support terms or names such as résumé, jalapeño, or René. But, depending on hardware and software support, some diacritical marks can be rendered by overwriting a letter with a backtick (`) or tilde (~).

The Internet Assigned Numbers Authority (IANA) prefers the name US-ASCII for this character encoding.

ASCII is one of the IEEE milestones.

ASCII is the standardisation of a seven-bit teleprinter code developed in part from earlier telegraph codes.

Work on the ASCII standard began in May 1961, when IBM engineer Bob Bemer submitted a proposal to the American Standards Association's (ASA) (now the American National Standards Institute or ANSI) X3.2 subcommittee. The first edition of the standard was published in 1963, contemporaneously with the introduction of the Teletype Model 33. It later underwent a major revision in 1967, and several further revisions until 1986. In contrast to earlier telegraph codes such as Baudot, ASCII was ordered for more convenient collation (especially alphabetical sorting of lists), and added controls for devices other than teleprinters.

ASCII was developed under the auspices of a committee of the American Standards Association (ASA), called the X3 committee, by its X3.2 (later X3L2) subcommittee, and later by that subcommittee's X3.2.4 working group (now INCITS). The ASA later became the United States of America Standards Institute (USASI) and ultimately became the American National Standards Institute (ANSI).