A Universally Unique Identifier, commonly referred to as a UUID or GUID, is a method of generating a moderately sized, unique identification value. Commonly used in registration systems of various types, these identifiers actually have multiple standards and can even contain data, despite appearing random.
Notes:
When decoding version 3 or version 5 UUIDs, two unknown nibbles will be marked with question marks in the Hash data. The first nibble is always completely unknown, but only the first two bits of the second nibble are unknown. The second two bits of the second unknown nibble will be listed above as "Second Nibble".
When decoding version 2 UUIDs, the Generated date value may be off by up to seven minutes.