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UUID v4 is a universally unique identifier generated using cryptographic random numbers, producing a 128-bit value typically displayed as 32 hexadecimal characters separated by hyphens (e.g., 550e8400-e29b-41d4-a716-446655440000). Version 4 UUIDs are the most commonly used type and are ideal for distributed systems where centralized ID generation is impractical.
UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) are essentially the same concept. GUID is the term used by Microsoft in Windows and .NET, while UUID is the standard term defined by RFC 4122. Both follow identical formatting rules and generation algorithms, and they are fully interchangeable across platforms.
UUID v4 has 122 random bits, giving approximately 5.3 x 10^36 possible values. The probability of generating two identical UUIDs is astronomically low — you would need to generate 1 billion UUIDs per second for about 85 years to have a 50% chance of a single collision. For all practical purposes, every UUID generated is guaranteed to be unique.
