The noexcept keyword

noexcept in C++ is a specifier that indicates whether a function is guaranteed not to throw an exception. If a function marked noexcept does throw an exception, the program's execution is immediately terminated by calling std::terminate.

It would also change the behavior of the std containers, like std::vector. If you garantee there is no exception throw, the vector knows that it move process would not be interrupted to leave the vector in an corrupted status, it can do the move without making copies to prevent the corruption.

This is why we want to use noexcept to the move contructor.