appendix D C++ Thread Library reference D.1 The <chrono> header The <chrono> header provides classes for representing points in time and duration s and clock classes, which act as a source of time_point s. Each clock has an is_steady static data member, which indicates whether it's a steady clock that advances at a uniform rate (and can't be adjusted). The std::chrono::steady_ clock class is the only clock guaranteed to be steady. Header contents namespace std { namespace chrono { template<typename Rep,typename Period = ratio<1>>