Thread Cancellation is a way where it's necessary sometimes to terminate a thread explicitly from another thread. In Windows we have a Function, it's TerminateThread() The function signature : BOOL WINAPI TerminateThread( _Inout_ HANDLE hThread, _In_ DWORD dwExitCode ); This function is always asynchronous. It never guarantees that the thread will always terminate by the time the function returns. This function never cleans up a stack of destroyed threads. So, it's not recommended to use this function until it's absolutely necessary. Note : As mentioned by Jeffrey Richter, Microsoft designed this API purposely implemented this way to terminate thread(s). This ensures that other threads are still running and accessing the terminated threads stack will not get an access violation. So, by leaving the terminated threads stack in memory, other threads which are accessing the stack of the killed thread can continue to execute. In Linux we have a function, i