What is UUID?
Short answer: A UUID (Universally Unique Identifier) is a 128-bit identifier expressed as 32 hexadecimal characters in 5 groups separated by hyphens (8-4-4-4-12).
Detailed explanation
UUIDs guarantee uniqueness without central coordination: any system can generate one and the probability of collision with another UUID anywhere in the world is practically zero (1 in 5.3 × 10^36 for UUID v4). 5 versions exist: v1 based on MAC + timestamp, v3 MD5 hash of namespace+name, v4 random (most used), v5 SHA-1 hash, v7 time-orderable (new).
Example
550e8400-e29b-41d4-a716-446655440000 (UUID v4)
Common use cases
- ▸Primary keys in distributed databases
- ▸Transaction IDs in APIs
- ▸File upload IDs
- ▸Session identifiers
- ▸Tracking IDs in analytics
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