A Version 7 UUID is a time-ordered universally unique identifier that embeds a millisecond-precision Unix timestamp followed by random data, so generated UUIDs sort in chronological order.
A Version 4 UUID is a universally unique identifier generated using random numbers from a secure random number generator.
A Version 5 UUID is a name-based universally unique identifier generated using a SHA-1 hash of a namespace identifier and a name. The same namespace and name will always produce the same Version 5 UUID.