A character code that defines every character in most of the speaking languages in the world. Although commonly thought to be only a two-byte coding system, Unicode characters can use only one byte, or up to four bytes, to hold a Unicode "code point." The code point is a unique number for a character or some character aspect such as an accent mark or ligature. Unicode supports more than a million code points, which are written with a "U" followed by a plus sign and the number in hex; for example, the word "Hello" is written U+0048 U+0065 U+006C U+006C U+006F (see hex chart).

Character Encoding Schemes
There are several formats for storing Unicode code points. When combined with the byte order of the hardware (big endian or little endian), they are known officially as "character encoding schemes." They are also known by their UTF acronyms, which stand for "Unicode Transformation Format" or "Universal Character Set Transformation Format." See byte order.

UTF-8 is widely used because the first 128 bits in the byte are ASCII, and although up to four bytes can be used, only one byte is required for use in the English speaking world. UTF-16 and UTF-32 use a fixed number of bytes. See DBCS.

   Unicode   ISO         Number
   Coding    10646       of      Byte
   Scheme    Equivalent  Bytes   Order**

   UTF-8                 1-4     BE or LE

   UTF-16    (UCS-2)     2       BE or LE
   UTF-16BE  (UCS-2)     2       BE
   UTF-16LE  (UCS-2)     2       LE

   UTF-32    (UCS-4)     4       BE or LE
   UTF-32BE  (UCS-4)     4       BE
   UTF-32LE  (UCS-4)     4       LE


   Pure ASCII
   (compatible with early 7-bit e-mail systems)

   UTF-7                 1-4     BE or LE


   **Byte Order (see byte order)
     BE = big endian
     LE = little endian