The computer may be defined as an electronic device that accept data, processes  the data using some set of predefined instructions, stores the result in it's memory, display it on the monitor screen and gives the output in a desired format.

    The two main constituents of the computer system are:-

1. Hardware.

2. Software.

   This is the physical part of the computer which comprises of the input devices, output devices and system unit.

Input devices: Input devices are the class of devices that provide information and instruction to the computer. E.g mouse, keyboard, light pen, joystick, scanner e.t.c

Output devices: output devices are the set of devices that are used to transfer processed data from the computers Central Processing Unit (CPU) to the user's monitor, speaker, printer, plotter e.t.c

Storage devices: Storage devices are devices that hold data, instruction and information for future use.

  Communication device is a hardware device that enables a computer to send(transmit) and receive data, instruction or information to and from or more computers.

1. It aids communication all over the world.

2. It aids business transaction.

3. It aids entertainment.

4. It gives instant access to information

5. It is the fastest means of Processing data.

6. It helps in the standard learning.

7. It allows information and idea exchange between individuals, societies and nations world wide.

8. It helps in security of lives and properties.

9. It helps in keeping medical records, diagnosis and treatment of disease.

10. It helps in traffic management and control.