UUID

A 128-bit label used to uniquely identify information in distributed systems without central coordination.

UUIDs provide a standardized 128-bit format (typically 32 hexadecimal characters) for generating unique identifiers across independent systems. RFC 9562 defines the current implementation standards: Version 4 leverages 122 bits of entropy for pure randomness, while Version 7 includes a millisecond-precision Unix timestamp for improved database indexing. These identifiers remove the bottleneck of a central registry: the probability of a collision is statistically zero for all practical applications. Engineers rely on them for primary keys in databases like PostgreSQL, session tracking, and resource mapping in microservice architectures.

https://datatracker.ietf.org/doc/html/rfc9562