UUID Generator

Universally Unique Identifier: A universally unique identifier is a 128-bit label used for information in computer systems. The term globally unique identifier is also used. When generated according to the standard methods, UUIDs are, for practical purposes, unique. Their uniqueness does not depend on a central registration authority or coordination between the parties generating them, unlike most other numbering schemes. While the probability that a UUID will be duplicated is not zero, it is generally considered close enough to zero to be negligible.[Wikipedia]