A keyboard is the most common way to input data; there are a variety of keyboard designs including traditional keyboards, laptop keyboards, virtual keyboards, and thumb keyboards.
Pointing devices are used to provide an intuitive interface with the system unit by accepting physical movements or gestures (pointing); there is a variety of different pointing devices such as the mouse, touch screens, game controllers, and a stylus.
Scanning devices are used to convert scanned text and images into a form for the system unit to process; there are only five types of scanning devices such as, optical scanners, care readers, RFID readers, bar code readers, and character and mark recognition devices.
Image Capturing Devices create/capture original images; these devices include digital cameras and webcams.
Audio-Input Devices convert sounds into a form that can be processed by the system unit; this device only contains voice recognition systems.