Stands for "American Standard Code for Information Interchange." ASCII character encoding provides a standard way to represent characters using numeric codes. These include upper and lower-case English letters, numbers, and punctuation symbols.
ASCII uses 7 bits to represent each character. For example, a capital "T" is represented by the number 84 and a lowercase "t" is represented by 116. Other keyboard keys are also mapped to standard ASCII values. For example, the Escape (ESC) key is represented as 27 and the Delete (DEL) key is represented as 32. ASCII codes may also be displayed as hexadecimal values instead of the decimal numbers listed above. For example, the ASCII value of the Escape key in hexadecimal is "1B" and the hexadecimal value of the Delete key is "7F."
Since ASCII uses 7 bits, it only supports 2^7, or 128 values. Therefore, the standard ASCII character set is limited to 128 characters. While this is enough to represent all standard English letters, numbers, and punctuation symbols, it is not sufficient to represent all special characters or characters from other languages. Even Extended ASCII, which supports 8 bit values, or 256 characters, does not include enough characters to accurately represent all languages. Therefore, other character sets, such as Latin-1 (ISO-8859-1), UTF-8, and UTF-16 are commonly used for documents and webpages that require more characters.
Updated: February 17, 2012