Source : Free On-Line Dictionary of Computing

character encoding
     
         (Or "character encoding scheme") A mapping of
        {binary} values to {code positions} and back; generally a 1:1
        ({bijective}) mapping.
     
        In the case of {ASCII}, this is generally a f(x)=x mapping:
        code point 65 maps to the byte value 65, and vice versa.  This
        is possible because ASCII uses only code positions
        representable as single bytes, i.e., values between 0 and 255,
        at most.  ({US-ASCII} only uses values 0 to 127, in fact.)
     
        {Unicode} and many {CJK} {coded character sets} use many more
        than 255 positions, requiring more complex mappings: sometimes
        the characters are mapped onto pairs of bytes (see {DBCS}).
        In many cases, this breaks programs that assume a one-to-one
        mapping of bytes to characters, and so, for example, treat any
        occurrance of the byte value 13 as a {carriage return}.  To
        avoid this problem, character encodings such as {UTF-8} were
        devised.
     
        (1998-10-18)