GUID (or UUID) is an acronym for 'Globally Unique Identifier' (or 'Universally Unique Identifier'). It is a 128-bit integer number used to identify resources.
Guid
s are Globally Unique Identifiers, also known as UUID's, Universally Unique Identifiers.
They are 128-bit pseudorandom values. There are so many valid Guid
s (about 10^18 Guid
s for each cell of every people on Earth) that if they are generated by a good pseudorandom algorithm, they can be considered unique in the whole universe by all practical means.
Guid
s are most often used as primary keys in databases. Their advantage is that you don't have to call the database to get a new ID that is (almost) guaranteed to be unique.