Wiktionary
n. (context computing English) any identifier that is guaranteed to be unique among all others used for objects and for a specific purpose (UID).
Wikipedia
With reference to a given (possibly implicit) set of objects, a unique identifier (UID) is any identifier which is guaranteed to be unique among all identifiers used for those objects and for a specific purpose. There are three main types of unique identifiers, each corresponding to a different generation strategy:
- serial numbers, assigned incrementally or sequentially
- random numbers, selected from a number space much larger than the maximum (or expected) number of objects to be identified. Although not really unique, some identifiers of this type may be appropriate for identifying objects in many practical applications and are, with abuse of language, still referred to as "unique"
- names or codes allocated by choice which are forced to be unique by keeping a central registry such as the EPC Information Services.
The above methods can be combined, hierarchically or singly, to create other generation schemes which guarantee uniqueness.
In many cases, a single object may have more than one unique identifier, each of which identifies it for a different purpose.
In relational databases, certain attributes of an entity that serve as unique identifiers are called primary keys.
Usage examples of "unique identifier".
If so, should each one receive a unique identifier (for instance, a unique ISBN)?
But starting in 1984, the company had to gear up a full-scale production line so that each new unit would have a unique identifier code built into its encryption algorithm.
First, you need to know that the SID number is a unique identifier and has a unique index, meaning the system won't allow you to enter a duplicate value.
It was signed with a unique identifier code that Dors recognized at once.