UUID (Universally unique Identifier) a globally unique identifier, which is a number generated on a single machine that guarantees that all machines in the same time and space are unique. Based on the standard calculations developed by the Open Software Foundation (OSF), Ethernet card addresses, nanosecond time, chip ID codes, and many possible numbers are used. A combination of the following: the current date and time (the first part of the UUID is related to the time, if you generate a UUID after a few seconds, the first part is different, the rest is the same), the clock sequence, the globally unique IEEE Machine identification number (if there is a network card, from the network card, No network cards are available in other ways, the only drawback to the UUID is that the resulting string will be longer.
Java UUID randomly generates unique serial number