A Security Identifier (SID) is a unique value used to identify a user or group in Windows operating systems. It is a string that is assigned to a user or group when they are created and remains the same for the lifetime of that user or group. The machine SID is the SID that is assigned to the computer itself. It is used to identify the computer when it is accessing resources on a network.
There are several ways to check the machine SID. One way is to use the command prompt. To do this, open a command prompt window and type the following command: