A UUID, or Universally unique identifier, is intended to uniquely identify information in a distributed environment. For the definition of UUID, see RFC 4122.

The creation of UUIDs does not require a centralized authority.

UUIDs are of relatively small size (128 bits, or 16 bytes). The common string representation (ex: 1d6c0810-2bd6-45f3-9890-0268422a6f14) needs 37 bytes. g_uuid_string_is_valid() can be used to check whether a string is a valid UUID.

The UUID specification defines 5 versions, and calling g_uuid_string_random() will generate a unique (or rather random) UUID of the most common version, version 4.

UUID support was added to GLib in version 2.52.