What Is a UUID and Why Is It Used?

What does UUID stand for?

UUID stands for Universally Unique Identifier. It is a 128-bit identifier designed so that independently generated values are extremely unlikely to collide.

A typical textual UUID looks like 550e8400-e29b-41d4-a716-446655440000.

Want to try the idea yourself? Use the UUID Generator.

Why use a UUID?

A database can use simple IDs such as 1, 2 and 3, but those numbers normally require a central system to decide the next value. UUIDs can be generated independently by different devices or services.

That makes them useful for distributed systems, records created offline, file identifiers and public-facing references.

If you want to explore this topic further, see Useful Online Generators: What Can You Create in Your Browser?.

Are UUIDs guaranteed unique?

The word “unique” is practical rather than magical. With appropriate UUID versions and generation methods, the probability of an accidental collision is so small that UUIDs are widely treated as unique for normal applications.

They should still be generated using a proper implementation rather than invented by typing random-looking characters.

Different UUID versions

UUID versions use different generation methods. For example, UUID v4 is based largely on random bits, while other versions can incorporate time or namespace-based information.

The correct version depends on the system’s requirements, including ordering, privacy and compatibility.

Generate UUIDs quickly

The UUID Generator creates correctly structured identifiers without needing a development environment.

If you are designing a database, remember that choosing UUIDs affects storage, indexing and how identifiers are exposed, so the choice should fit the application rather than being automatic.