A UUID is 128 bits. Here is what each of them is for.
9b2c3f4e8d174a6b9f3e2c1d0e5a7b8c
A UUIDv4, the kind most tools print. Watch the fields appear, or press → to step through them.
pick a version
v4random
919108f752d143209bacf847db4148a8
v7time, then random · sorts
017f22e279b07cc398c4dc0c0c07398f
v1time, clock, MAC · 1990s
c232ab00941411ecb3c89f6bdeced846
v6v1 reordered · sorts
1ec9414c232a6b00b3c89f6bdeced846
v3MD5 of a name
5df418813aed351588a72f4a814cf09e
v5SHA-1 of a name
2ed6657de927568b95e12665a8aea6a2
v8your own bits
2489e9ad2ee28e008ec932d5f69181c0
Nilnil, max, variants
00000000000000000000000000000000