What is "guid"

A GUID is a Global Unique Identifier, is a special type of identifier used in software applications to provide a reference number which will be unique in any context such as for example an internal reference definition for a type of access point in a software application or for creating unique keys in a database.

Although each generated GUID has no guarantee of being unique, the total number of unique keys (2 128 or ~3.4 10 38) is so large that the probability of the same number being generated twice is very small.