globally unique identifier (GUID - globally unique identifier), GUID is a 128-bit globally unique identifier (GUID - globally unique identifier), and GUID is a 128-bit binary number (16 bytes) that can be used for all computers and networks that require unique identifiers. The possibility of this identifier being duplicated is very small. The format of the GUID is "xxxxxxx-xxxx-xxxx-xxxxxxxxxxxxxxxxxxxxxxxx", where each x is a hexadecimal number in the range 0-9 or a-f.