A computer is a combination of hardware and software that lets the user to work with a computer. The hardware is the physical equipment .The software is asset of programs that allows hardware to do its job.

Hardware: - Hardware in a computer system is the combination of devices that can be seen and touched. Every computer small or large is made of four basic types of devices: input devices, output devices, the central processing unit (CPU) and auxiliary or secondary storage devices.

Software:-The software of a computer system is the combination of programs written to make the computer a multipurpose machine. It is divided in to two different types: system software and application software.

System Software consists of the set of programs that serve the computer itself; that is, its primary purpose is to support the computer. System software supports the development of other application software, supports the execution of other applications, monitors various resources such as CPU, memory, peripherals etc It generally consists of an operating system and set of sub programs, such as disk copy, that provide general functionality.

Application Software consists of programs that are written to solve specific problem or do a specific task. The programs included in application software package are called application programs

An operating system is a program that manages the computer hardware. It provides a basis for application programs and acts as an intermediately between a user of a computer and computer hardware. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers. Operating systems provide a software platform on top of which application programs run.