<P> A computer program is a general structured collection of instruction sequences that perform a specific task when executed by a computer . A computer requires programs to function . </P> <P> A computer program is usually written by a computer programmer in a programming language . From the program in its human - readable form of source code, a compiler can derive machine code--a form consisting of instructions that the computer can directly execute . Alternatively, a computer program may be executed with the aid of an interpreter . </P> <P> The evolution of a process is directed by a pattern of rules called a program . People create programs to direct processes . </P>

Built-in set of machine code instructions of computer are called