What is a UUID?

A UUID (Universally unique identifier) is a 128 bit number which is used to uniquely identify something. The UUIDs can be generated without a use of a centralized authority. The main idea being that the UUIDs created always be unique. There will be no duplication of the same ID. Duplication of the same ID are extremely unlikely to happen. At least in a single application space.

There are mainly three different UUIDs. They are version1, version4 and Nil or empty UUID