What is a GUID?
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. The term GUID is generally
used by developers working with Microsoft technologies, while
UUID is used everywhere else.
How unique is a GUID?
128-bits is big enough and the generation algorithm is unique
enough that if 1,000,000,000 GUIDs per second were generated for
1 year the probability of a duplicate would be only 50%. Or if
every human on Earth generated 600,000,000 GUIDs there would only
be a 50% probability of a duplicate.
How are GUIDs used?
GUIDs are used in enterprise software development in C#, Java,
and C++ as database keys, component identifiers, or just about
anywhere else a truly unique identifier is required. GUIDs are
also used to identify all interfaces and objects in COM