Question 1

What is a UUID?

Accepted Answer

A UUID (Universally Unique Identifier) is a 128-bit identifier that is guaranteed to be unique across space and time. UUIDs are standardized by RFC 4122 and are used in many computer systems as database keys, session identifiers, and more.

Question 2

Which UUID version should I use?

Accepted Answer

For most applications, UUID version 4 (random) is recommended as it provides the best balance of uniqueness and security. Use version 5 when you need deterministic UUIDs based on names, version 1 when timestamp ordering is important, version 3 for MD5-based name UUIDs, and version 7 for time-ordered UUIDs with high uniqueness.

Question 3

Are UUIDs secure for sensitive applications?

Accepted Answer

UUID version 4 is generated using cryptographically secure random number generators and is suitable for most security-sensitive applications. However, version 1 may leak information about the generating system and should be used with caution in security-critical contexts. For highly sensitive applications, consider using a cryptographic random generator directly.

Security Strength:

Version 4 (Random)

UUID Use Cases

Usage Tips