A universally unique identifier (UUID) is a 128-bit number used to uniquely identify information in computer systems.

UUIDs are generated in such a way that they are highly unlikely to be duplicated, even if generated simultaneously on different systems.

This makes them ideal for use in distributed systems where unique identification is crucial. UUIDs are commonly used in software development, particularly in databases, as primary keys for records.

They are also used in various other applications such as messaging systems, file systems, and network protocols. The format of a UUID is standardized by the Internet Engineering Task Force (IETF) in RFC 4122.

A UUID is typically represented as a string of 32 hexadecimal digits separated by hyphens, such as "550e8400-e29b-41d4-a716-446655440000". One of the key benefits of using UUIDs is that they can be generated without the need for a centralized authority, unlike other types of unique identifiers such as serial numbers or timestamps.

This makes them particularly useful in distributed systems where multiple entities need to generate unique identifiers independently. Overall, UUIDs play a crucial role in ensuring data integrity and uniqueness in computer systems, making them a valuable tool for software developers and system architects.