- Also called software. A set of instructions or programs, which when translated and executed cause a computer to perform specific operations. Software is usually classified into two general categories, which are system software, and application software. system software includes control programs, such as the operating system, while application software refers to programs which perform specific tasks, such as a word processor. Although program and software are used mostly synonymously, software is a bit more of a general term, as it is used to differentiate from the physical equipment of a computer, the hardware, from the instructions which tell a computer what to do, the software. An application is both a program and software, but when using the term software it usually refers to multiple application programs, or application programs in general, in which case they are called application software.