Software makes the computer a workable machine. It sits between the user and the hardware (electronic components of the computer) and work as a translator.

 Computer software is normally classified in to two broad categories:

 Application software is usually custom written or packaged and it enables the user to perform their work (example Microsoft Word). System software enables the computer to run application software (example Microsoft Windows).

Application Software 

An Application Software also referred to as an application package, is a set of programs designed to carry out operations for a specified purpose. For example, a payroll package produces pay slips as the major output and an application package for processing Examination results produce mark sheets as the major output along with some other statistical reports. Similarly, a program written by a scientist to solve his particular research problem is also application software. The programs that constitute an application package are known as application programs and the person who prepares application programs is known as an application programmer. 

System Software (Operating System)

 When you switch on the computer, the programs stored in the Read -Only Memory (ROM) is executed which activates different units of the computer. This makes the computer ready for you to work on it. These programs are called system software. Therefore, system software may be defined as a set of programs designed to control the operation of a computer system. Therefore, system software is also called as Operating System. System Software generally performs tasks such as controlling all operations required to move data in and out of the computer. It communicates with printers, card readers’ disk etc., and monitors the use of hardware such as memory, CPU etc. A computer cannot work without an operating system. System Software allows application software to be run on the computer with less time and effort. Application software cannot be run without having system software.

Some common operating systems are DOS, various versions of Windows, OS/2, UNIX, and Linux. All these behave in very different ways and have different hardware requirements and they will not run on all machines. The creation of systems software is a complex task. Systems programmers, who prepare systems software, are highly trained computer specialists and important members of the computer architectural team. Because of its technical complexity, systems software is rarely developed in-house. They are normally developed and distributed by computer manufacturers.