What is a UUID?

A Universally Unique Identifier (UUID) is a 128-bit identifier used to uniquely identify information in computer systems. UUID v4 uses random values, making each one unique without requiring a central authority.

When to Use UUIDs

• Primary keys in databases
• Generating unique identifiers for test data
• Session IDs and tracking tokens
• Any situation requiring globally unique IDs

UUID Format

Format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx

• 'x' = hexadecimal digit (0-9, a-f)
• 'y' = hexadecimal digit (8, 9, a, or b)
• Version 4 = randomly generated

Examples

Example: UUID v4 → 550e8400-e29b-41d4-a716-446655440000