: Multiprocessing refers to two or more instructions running parallel to two or more central processors or CPUs. These CPUs can follow different instructions for a program at the same time, or they can perform completely different programs. The main difference between a multiprocessing system and a multiprogramming system is that in multiprogramming only one processor is used , and in multiprocessing multiple processors are used. Multiprocessing systems are used in mini and mainframe computers. Multiprocessing methods are extremely fast. This method can be relied on as more than one processor is used , because even if one processor goes bad, the work does not stop completely. Only the speed of work decreases. Multiprocessing systems are used in spacecraft , power plants , factories.