Prior to execution, a program must first be written. This is generally done in source code, which is then compiled at compile time (and statically linked at link time) to an executable. This executable is then invoked, most often by an operating system, which loads the program into memory (load time), possibly performs dynamic linking, and then begins execution by moving control to the entry point of the program; all these steps depend on the Application Binary Interface of the operating system. At this point execution begins and the program enters run time. The program then runs until it ends, either normal termination or a crash.
