A UUID (Universally Unique Identifier) is a 128-bit identifier that is guaranteed to be unique across space and time. UUIDs are commonly used in software development to uniquely identify records, resources, and entities without requiring a central authority.

What is the difference between UUID v1, v4, and v5?

UUID v1 is generated using the current timestamp and the machine's MAC address. UUID v4 is generated using random or pseudo-random numbers, making it the most commonly used version. UUID v5 uses a namespace and a name hashed with SHA-1 to produce a deterministic, reproducible UUID.

Is UUID the same as GUID?

Yes, GUID (Globally Unique Identifier) is Microsoft's implementation of the UUID standard. They are functionally identical and follow the same RFC 4122 specification.

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What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information without requiring a central authority. They are commonly used as primary keys in databases, session tokens, resource identifiers in APIs, and anywhere a globally unique ID is needed.

UUID Versions

Version	Method	Use Case
v1	Timestamp + MAC address	Time-ordered, sortable IDs
v4	Random numbers	Most common; general purpose
v5	SHA-1 hash of namespace + name	Deterministic (same input = same UUID)

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