locally unique identifier (LUID)

A Locally Unique Identifier (LUID) is a logon identifier that is used to identify the logon to a session.

Such a Locally Unique Identifier (LUID) remains valid for the duration of the session until the user logs out again with a logout. The ID number is assigned once for this session; no other session has the same identification number. However, it is possible that the ID numbers are reset after a shutdown of the computer.