Input devices that function as part of a computer system come in many different varieties. Some input devices have a broad range of functionality and, therefore, you will find those types of input devices on most if not all computer systems. Others have more specialised functions, such as for use with graphic or audio applications.
With reference to computers, the term input device describes an instrument with the purpose of performing the tasks of conveying data into the computer system, as indicated at the Compukiss and Expedient websites.
The most widely known input devices for computers include the keyboard, the mouse and certain alternatives to a mouse. Some more commonly known mouse substitutes include trackballs and joysticks.
More specialised input devices also include some mouse alternatives such as light pens, touch pads and drawing tablets. A microphone, which allows communicating audio data to the computer, also provides an example of a less commonly used input device.