Unique identifier
From Wikipedia, the free encyclopedia
Unique identifiers are codes used to identify objects that are unique within a given context. Where the context is unlimited, they are called globally unique. There are three main ways of creating unique identifiers:
- serial numbers, allocated in sequence
- random numbers selected from a number space much larger than the expected number of objects to be identified. Although not guaranteed to be unique, identifiers chosen in this way can be shown to be almost certain to be unique.
- meaningful names or codes allocated by choice which are forced to be unique by keeping a central registry
All of the above methods can be combined hierarchically, singly or in combination with one another, to create scalable schemes for creating unique identifiers.
In many cases, a single object may have more than one unique identifer, each of which identifies it for a different purpose.
