ASCII is limited to 128 characters, Unicode and the UCS support more characters by separating the concepts of unique identification (using natural numbers called code points) and encoding (to 8-, 16-, or 32-bit binary formats, called UTF-8, UTF-16, and UTF-32, respectively). ASCII was incorporated into the Unicode (1991) character set as the first 128 symbols, so the 7-bit ASCII characters have the same numeric codes in both sets. This allows UTF-8 to be backward compatible with 7-bit ASCII, as a UTF-8 file containing only ASCII characters is identical to an ASCII file containing the same sequence of characters. Even more importantly, forward compatibility is ensured as software that recognizes only 7-bit ASCII characters as special and does not alter bytes with the highest bit set (as is often done to support 8-bit ASCII extensions such as ISO-8859-1) will preserve UTF-8 data unchanged. See also 3568 ASCII, an asteroid named after the character encoding Alt codes Ascii85 ASCII art ASCII Ribbon Campaign Basic Latin (Unicode block) (ASCII as a subset of Unicode) Extended ASCII HTML decimal character rendering Jargon File, a glossary of computer programmer slang which includes a list of common slang names for ASCII characters List of computer character sets List of Unicode characters Notes References Further reading from: (facsimile, not machine readable) External links Computer-related introductions in 1963 Character sets Character encoding Latin-script representations Presentation layer protocols American National Standards Institute standards