ISO C++ library mutex thread future condition_variable Facilities for concurrent operation, and control thereof. All items are declared in one of four standard header files. In header mutex, class template mutex and variants, class once_flag, and class template unique_lock. In header condition_variable, classes condition_variable and condition_variable_any. In header thread, class thread and namespace this_thread. In header future, class template future and class template shared_future, class template promise, and packaged_task. Full API details.