Lesson 1
What Is a UUID?
Why UUIDs exist and where developers use them.
A UUID is a Universally Unique Identifier: a 128-bit value usually written as 32 hexadecimal characters in five groups, such as 550e8400-e29b-41d4-a716-446655440000.
Developers use UUIDs when IDs must be generated independently:
- Client-created records before they reach a server
- Test fixtures and seed data
- Public identifiers that should not reveal database row counts
- Correlation IDs in logs and distributed traces
- API examples where a realistic identifier is useful
UUIDs are not magic security tokens. They are identifiers, not proof of permission. Use access control and cryptographic tokens for authorization.