What is an UUID / GUID
An answer to "What is an UUID?" would be "A GUID" this answer wouldn't
help most of us any further though.
UUID stands for Universally Unique IDentifier, GUID for Globally Unique
IDentifier. The correct way to construct these identifiers is described
in RFC 4122,
ITU-T Rec. X.667
The main function of an UUID is being unique.
What is it used for:
UUIDs are applied for identification purposes in a number of fields in
the computer industry.
Possible uses are (but are not limited to):
To ensure nobody else would - by accident - provide something
- The identifiers in the windows registry.
- Identifiers used in databases.
- Identifiers used in RPC (COM, CORBA) (remote procedure calls)
What does it look like:
UUIDs are basically 128 bit numbers, normally presented in the
following hexadecimal - grouped form:
The nil UUID:
A special type of UUID is guaranteed to not be unique, and easily
recognised. This is the nil UUID: 00000000-0000-0000-0000-000000000000.
It can serve to clear UUIDs and as a template while cunstructing new
Only for version 1 UUIDs, third group must start with a 1.
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