To add to what others have said, additional characteristics of a Win32 critical section: - It is purely an in-process lock, and originally the main way of arbi

To add to what others have said, additional characteristics of a Win32 critical section: - It is purely an in-process lock, and originally the main way of arbitrating access to shared memory within a process. - It is counted and can be recursively locked. - It defaults to simple blocking, but can also be configured to do some amount of spin-waiting before blocking. - CritSecs are registered in a global debug list that can be accessed by debuggers. WinDbg's !locks command can display all locked critical sections in a process and which threads have locked them. Originally in Win32, there were only two types of lock, the critical section for in-process locking, and the mutex for cross-process or named locks. Vista added the slim reader/writer lock, which is a much lighter weight, pointer-sized lock that uses the more modern wait-on-address approach to locking.