UUID (Universally Unique Identifier)

Definition

UUIDs are 128-bit numbers used to uniquely identify information in computer systems. They are standardized by IETF RFC 4122 and typically displayed as 36 characters in 8-4-4-4-12 format. UUID v4 uses random numbers (122 random bits), providing approximately 5.3 × 10³⁶ possible values — enough to assign trillions of unique IDs per second for billions of years. UUID v7 (RFC 9562) uses time-ordered values, improving database index performance by ensuring sequential insertion.