Question 1

What is UUID?

Accepted Answer

UUID (Universally Unique Identifier) is a 128-bit identifier that is unique across space and time, commonly used in distributed systems for generating unique keys.

Question 2

Which UUID version should I use?

Accepted Answer

Version 4 (random) is most commonly used and recommended for most applications. Version 1 is time-based, while versions 3 and 5 are name-based using MD5 and SHA-1 respectively.

Question 3

What is the difference between UUID and GUID?

Accepted Answer

UUID and GUID (Globally Unique Identifier) are essentially the same thing. GUID is Microsoft's implementation of the UUID standard. Both use the same format: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.

Question 4

Are UUIDs truly unique?

Accepted Answer

For UUID v4 (random), the probability of collision is astronomically low (about 1 in 2^122). While not mathematically impossible, duplicate UUIDs are practically never encountered in real-world applications.

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