**Universally Unique Identifier - a 128-bit identifier**
UUID stands for "Universally Unique Identifier". The idea is that it's a [[Surrogate Keys]] that function for _any_ element of _any_ table, resource, system, or whatever. It's **universal**.
It was developed my Microsoft, and is typically 128-bits. They are supported by Microsoft SQL Server, MySQL, PostgreSQL, MongoDB, and others.
# Format
There are 5 Versions of UUIDs. Some are random. Some are time-indexed. They generally are broken into 5 groups of **hexadecimal** characters, delimited by hyphens. Like so:
`123e4567-e89b-12d3-a456-426614174000`
What each of those hyphen-delimited groups _means_ depends on the version of the UUID.
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# More
## Source
- [Universally unique identifier - Wikipedia](https://en.wikipedia.org/wiki/Universally_unique_identifier)
## Related
- [[SysML]]
- [[Primary Key]]
- [[Surrogate Keys]]
- [[UUIDs in the Wild]]