Any information that you enter into computer which is allowed by computer only is a input device. List of input devices are:

Keyboard

Keyboard is very common input device which helps you to input data to computer. Layout is seems like a traditional typewriter having some keys and there functions. Some of the important keys are typing key these key include letters from A-Z and digits from 0-9, numeric keypad, functional key, control key and special purpose key.

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Mouse

Popular pointing device used for controlling the cursor having a small palm size box and a ball to scroll up and down. Basically it has two buttons left and right. Advantage is it is faster than arrow key of keyboard.

Joystick

It is also known as pointing device which is used to move cursor position on monitor screen. Function is similar as mouse especially use for computer aided designing (CAD) and playing game in computer.

Light pen

This device is similar to pen which is used to display menu items and draw pictures on monitor screen. A small tube of a pen consist photo cell and optical system.

Scanner

It is work like a photocopy machine it is used when some information is available on paper and it to be transferred to a hard disc to manipulate data.

Bar card reader

It is a device which is used to read bar coded data. This data is generally used for labelling goods, numbering the books etc.

Optical mark reader

This is special type of optical scanner that recognize a mark made by pen or pencil. Used when you have to highlight few alternatives. Especially used for checking the marksheets.

Track Ball

Track ball is a kind of input device which is used at the place of mouse in notepad and laptop computers. This ball in half inserted in the system and by moving fingers on it cursor or pointer can be moved or operate. This device require less space as compared to mouse because whole of the device is not moving. It comes in many shapes that depends on the system.

Digitizer

This device convert information from analog to digital. It can also convert signal from the television or camera into a series of numbers that could be stored in a computer. It also convert graphic or pictorial data into binary inputs so it is also known as tablet and graphic tablet. It is used for fine work of drawing and image manipulation application.

Microphone

This device take sound as input and store in digital form. Microphones is used for application like mixing music and adding sound to multimedia presentation.

Magnetic Ink Card Reader (MICR)

This device is generally used by banks to process large number of cheques every day. There is a special type of ink printed on cheques, so special type of ink contain particle which is readable by machine the process of reading the special ink by machine is called Magnetic Ink Card Reader(MICR). Advantage is it is fast and less error prone.

Optical character reader(OCR)

This device scan text character by character and read printed text and convert that into machine readable code and store on the system memory.