A universally unique identifier (UUID) is an identifier standard used in software construction. The meaning of each bit is defined by any of several variants. It is a 128-bit value.
UUID form: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx, Here M indicate the UUID version, N indicates the variant. UUID has five versions, Version 1 (MAC address & date-time), Version 2 (DCE Security), Version 3 (MD5 hash & namespace), Version 4 (random), Version 5 (SHA-1 hash & namespace). The Generator could generates the latest three versions.