ASCII is the abbreviation for American Standard Code for Information Interchange, a character encoding standard for electronic communication. Originally created for teletype machines, ASCII codes represent text in telecommunications equipment, computers, and other devices.
Based on the English alphabet, ASCII encodes 128 specified characters into seven-bit integers. Ninety-five of the encoded characters are printable: these include the digits 0 to 9, lowercase letters a to z, uppercase letters A to Z, and punctuation symbols. In addition, the original ASCII specification included 33 non-printing control codes which originated with Teletype machines; most of these are now obsolete, although a few are still commonly used, such as the carriage return, line feed and tab codes.
As computer technology spread throughout the world, different standards bodies and corporations developed many variations of ASCII. These newer character-encoding schemes often are based on ASCII, but typically support additional characters, e.g. to facilitate the expression of non-English languages that use Roman-based alphabets, scripts and symbols.
The most common character set supplanting ASCII nowadays is Unicode. While Unicode still incorporates the original ASCII codes, its version Unicode 11.0 from June 2018 contains a repertoire of 137,439 characters covering 146 modern and historic scripts, as well as multiple symbol sets and emoji.