A universally unique identifier is a 128-bit label used for information in computer systems. The term globally unique identifier is also used. When generated according to the standard methods, UUIDs are, for practical purposes, unique.
A Version 4 UUID is a universally unique identifier that is generated using random numbers. The Version 4 UUIDs produced by this site were generated using a secure random number generator.
A Version 1 UUID is a universally unique identifier that is generated using a timestamp and the MAC address of the computer on which it was generated.