WordNet (r) 3.0 (2006):

American Standard Code for Information Interchange
    n 1: (computer science) a code for information exchange between
         computers made by different companies; a string of 7 binary
         digits represents each character; used in most
         microcomputers [syn: American Standard Code for
         Information Interchange, ASCII]

The Free On-line Dictionary of Computing (30 December 2018):

American Standard Code for Information Interchange
ASCII

    The basis of character sets used in almost
   all present-day computers.  US-ASCII uses only the lower seven
   bits (character points 0 to 127) to convey some control
   codes, space, numbers, most basic punctuation, and unaccented
   letters a-z and A-Z.  More modern coded character sets (e.g.,
   Latin-1, Unicode) define extensions to ASCII for values above
   127 for conveying special Latin characters (like accented
   characters, or German ess-tsett), characters from non-Latin
   writing systems (e.g., Cyrillic, or Han characters), and such
   desirable glyphs as distinct open- and close-quotation marks.
   ASCII replaced earlier systems such as EBCDIC and Baudot,
   which used fewer bytes, but were each broken in their own way.

   Computers are much pickier about spelling than humans; thus,
   hackers need to be very precise when talking about characters,
   and have developed a considerable amount of verbal shorthand for
   them.  Every character has one or more names - some formal, some
   concise, some silly.

   Individual characters are listed in this dictionary with
   alternative names from revision 2.3 of the Usenet ASCII
   pronunciation guide in rough order of popularity, including
   their official ITU-T names and the particularly silly names
   introduced by INTERCAL.

   See V ampersand, asterisk, back quote, backslash,
   caret, colon, comma, commercial at, control-C,
   dollar, dot, double quote, equals, exclamation mark,
   greater than, hash, left bracket, left parenthesis,
   less than, minus, parentheses, oblique stroke,
   percent, plus, question mark, right brace, right
   brace, right bracket, right parenthesis, semicolon,
   single quote, space, tilde, underscore, vertical
   bar, zero.

   Some other common usages cause odd overlaps.  The "#", "$", ">",
   and "&" characters, for example, were all pronounced "hex" in
   different communities because various assemblers use them as a
   prefix tag for hexadecimal constants (in particular, "#" in many
   assembler-programming cultures, "$" in the 6502 world, ">" at
   Texas Instruments, and "&" on the BBC Micro, Acorn
   Archimedes, Sinclair, and some Zilog Z80 machines).  See also
   splat.

   The inability of US-ASCII to correctly represent nearly any
   language other than English became an obvious and intolerable
   misfeature as computer use outside the US and UK became the rule
   rather than the exception (see software rot).  And so national
   extensions to US-ASCII were developed, such as Latin-1.

   Hardware and software from the US continued for some time to
   embody the assumption that US-ASCII is the universal character set
   and that words of text consist entirely of byte values 65-90 and
   97-122 (A-Z and a-z); this is a major irritant to people who want
   to use a character set suited to their own languages.  Perversely,
   though, efforts to solve this problem by proliferating sets of
   national characters produced an evolutionary pressure (especially
   in protocol design, e.g., the URL standard) to stick to
   US-ASCII as a subset common to all those in use, and therefore
   to stick to English as the language encodable with the common
   subset of all the ASCII dialects.  This basic problem with having
   a multiplicity of national character sets ended up being a prime
   justification for Unicode, which was designed, ostensibly, to be
   the *one* ASCII extension anyone will need.

   A system is described as "eight-bit clean" if it doesn't
   mangle text with byte values above 127, as some older systems
   did.

   See also ASCII character table, Yu-Shiang Whole Fish.

   (2014-10-05)