A SID, short for Security Identifier, is a number used to identify user, group, and computer accounts in Windows.
How to find your users' security ID (SID) in Windows 10?
They are created when the account is first created in Windows. No two SIDs on a computer are ever the same.
The term security ID is sometimes used in place of SID or security ID.
Users (you and I) refer to accounts by their account name, such as "Tim" or "Dad." However, Windows uses the SID when processing accounts internally.
