Explain any three types of input devices.

The three types of input devices are as follows:

1. Keyboard — A keyboard is the input device which directly enters the data in the form of letters, digits and commands into the computer. QWERTY keyboard is the commonly-used keyboard.

2. Mouse — A mouse is a pointing device with a roller at its base, used for moving a pointer on a computer monitor. It converts the movements of the user's hand into a unique set of binary digits representing the position of the mouse at a particular instant. When a user moves a mouse across a flat surface, the pointer moves in the direction of the mouse's movement.

3. Light Pen — A light pen is a pointing device that can be used to select anything on the computer screen by simply pointing at it or for drawing figures directly on the screen. It consists of a photocell mounted on a pen-shaped tube called stylus. It is capable of sensing a position on the screen when its tip touches the screen. Clicking is performed by pressing the pen on the screen. A light pen is mostly used by engineers, architects or designers.