Term: guid [Globally Unique IDentifier]

GUID (typically pronounced “gwid”) is an acronym for Globally Unique IDentifier.

A GUID is nothing more than a 128-bit number, though it’s often displayed as a sequence of 32 hexadecimal digits with dash separators and enclosed in curly braces. Example:

{AFD62796-267B-4c65-80FA-2F02B096D24B}

A 128-bit number has 340,282,366,920,938,463,463,374,607,431,768,211,456 possible values.

GUIDs are generated using algorithms to ensure sufficient randomness and diversity that the “unique” portion of the name is as true as possible. When generated properly, it is statistically nearly impossible that two GUIDs will be created with the same value. (Unfortunately, less-than-proper techniques, including simply copying existing values, are in occasional use.)

GUIDs are used to identify many different things, and are most frequently used when uniqueness of identification is important, difficult, or inconvenient to ensure by other means.