Glossary
SID
Security Identifier — the unique identifier Windows assigns to every security principal (user, group, computer).
Security Identifier — the unique identifier Windows assigns to every security principal (user, group, computer). Built-in SIDs are well-known: S-1-5-18 is LocalSystem, S-1-5-19 is LocalService, S-1-5-20 is NetworkService. Domain SIDs end in a Relative ID (RID); -500 is the local Administrator, -501 is Guest.