A mutex implements a form of synchronization called mutual exclusion, where the presence of one thread within a protected or critical section of code prohibits the entry of other threads into that section. A mutex can be used to synchronize thread access to shared resources and data.

A thread must acquire ownership of a mutex prior to entering the section of code protected by the mutex. Once a thread is granted ownership of the mutex, it is allowed to proceed into the protected section of code. Other threads entering this same section also attempt to acquire ownership of the mutex, but these threads are forced to wait until the current owner exits the section of code and releases ownership of the mutex.

The RWMutexLock class is the basic mutex mechanism for the Synchronization package. See The RWMutexLock Class for more information about this class.