Question: what are commonest types of input device?
Answer: Keyboard. Keyboard is the most common and very popular input device which helps to input data to the computer. ... 
Mouse. Mouse is the most popular pointing device. ... 
Joystick. Joystick is also a pointing device, which is used to move the cursor position on a monitor screen. ... 
Light Pen. ... 
Track Ball. ... 
Scanner. ... 
Digitizer. ... 
Microphone.