Overview A Universally Unique Identifier (UUID) is a 128-bit identifier described in Internet Engineering Task Force RFC 4122: A Universally Unique IDentifier (UUID) URN Namespace . Generators for versions 1,3,4 and 5 UUID's are provided. The value held in a UUID is represented by a specific hexadecimal format of the binary fields. An example UUID string representation is: F81D4FAE-7DEC-11D0-A765-