A UUID (Universally Unique Identifier) is a 128-bit value or 36-character alphanumeric string that can be used to identify information across a computer system. UUIDs are designed to be globally unique and are often used to identify rows of data within a database table, where each row is assigned a specific UUID. For example, most mobile devices have a unique ID, also called a UUID, assigned at the time of manufacture for identification purposes. UUIDs are sometimes called "GUID" or "Globally Unique Identifiers". The term "GUID" is also used, mostly in Microsoft systems. The specification for UUIDs was originally created by Microsoft and standardized by both the IETF and ITU.