GUID (globally unique identifier)

A 16-byte value generated from the unique identifier on a device, the current date and time, and a sequence number. A GUID is used to identify a particular device or component. In Active Directory, GUIDs are automatically generated for every object (for example, user, group, computer, and so on), and that value is guaranteed to never change. In Exchange, the Recipient Update Service automatically generates GUIDs for every mailbox. Also referred to as a Universally Unique Identifier (UUI). [Exchange 2003]

A 16-byte value generated from the unique identifier on a device, the current date and time, and a sequence number. A GUID is used to identify a particular device or component. In Active Directory, GUIDs are automatically generated for every object (for example, user, group, computer, and so on), and that value is guaranteed to never change. Also referred to as a Universally Unique Identifier (UUI). [Exchange 2007]