A computer system, is a collection of several hardware components that performs the
basic system functions of input, processing, output, storage and control.
The hardware components of a computer system include input and output devices, the
CPU, and primary and secondary storage devices. The selection of these hardware
components depends on organisational goals and IS objectives.

Input devices convert data into electronic form for direct entry or through a
telecommunications network into a computer system. Popular input devices include
keyboard and the mouse.

The ability to process data is a critical aspect of a computer system, in which processing
is accomplished by an interplay between one or more of the central processing units and
primary storage (main memory). These two are housed together in the same box orcabinet, named the system unit. Other computer system devices are linked to the system
unit directly or indirectly.

Output devices convert electronic information produced by the computer system into
human understandable form for presentation for end users. Common output devices are
monitors and printers.

The computer operates based on a set of instructions given by the user. If it is a data
processing application, data will be fed to the computer with a set of necessary
instructions which is called a computer program. These data and programs, when they
are fed, should be stored inside the computer during the processing. But the computer
will generally store these information, data and programs temporarily. When the
computer is switched off, information stored will disappear. This storage is referred to as
the Primary storage where program instructions and data are held immediately before,
during and after execution by the CPU. Before you switch off your computer, data and
instructions should be permanently stored for later or future use. The devices used to
store data in a relatively permanent form are called Secondary storage. Thus, there are
two types of storage devices namely:

Controlling of all operations like input, processing, storage and output are performed by
the control unit. The control unit takes care of step by step processing of all operations
inside the computer. It controls how instructions are executed and the above operations
are performed.