The American Standard Code for Information Interchange (ASCII – pronounced Ask-ee”) is a character encoding standard used for representing text and control characters in computers and other devices that use text. It was developed in the early days of computing, during the 1960s and 1970s, by the American National Standards Institute (ANSI).
Key points about ASCII:
- Character Encoding: ASCII uses a 7-bit encoding scheme to represent a set of 128 characters. These characters include uppercase and lowercase letters (A-Z, a-z), digits (0-9), punctuation marks, control characters (such as carriage return, line feed, and tab), and a few special characters.
- Character Mapping: Each character in the ASCII set is assigned a unique numeric value ranging from 0 to 127. For example, the capital letter ‘A’ is represented by the numeric value 65, ‘B’ by 66, ‘a’ by 97, ‘b’ by 98, and so on.
- Limited Character Set: ASCII has a limited character set primarily designed for the English language and lacks characters necessary for other languages, accents, symbols, or non-printable characters.
- Standardisation: ASCII became a widely accepted standard for character encoding, allowing different computers and systems to exchange and interpret text data uniformly.
- Extended ASCII: To accommodate additional characters and symbols needed for different languages and applications, various extended versions of ASCII were developed, such as ISO-8859-1 (Latin-1) and Windows-1252, which used the eighth bit to represent additional characters beyond the original 128.
- Legacy Usage: While ASCII laid the groundwork for text encoding, its usage has diminished with the emergence of more versatile and comprehensive character encoding standards like Unicode. However, ASCII remains fundamental, and its basic character set is a subset of Unicode.