A UUID (universally unique identifier) is an identifier standard used in software construction is a 16-byte (128-bit) number. The UUIDs is to enable distributed systems to uniquely identify information without significant central coordination.
The Microsoft's globally unique identifiers (GUID) is the most widespread use of this standard.
The GUID/UUId form looks like 432c4973-213c-3e5e-bce4-d1080a92bfc7.