Input devices

The keyboard is used to input data using alphanumeric keys and special keys such as $ or %. It also allows the user to input commands such as Ctrl/Alt/Delete pressed together to lock the computer. 

The mouse is a point and click device that allows the user to communicate with the computer by placing a cursor on the screen that the computer tracks and the user clicks on displays onscreen such as buttons. 

A scanner allows a user to make a digital copy of a physical document or photograph that the computer can read or display. scanners are also used in biometrics for fingerprint or iris scanners for security passes. 

Sensors are physical devices such as thermometers or motion sensors that send signals to the computer so it can decide whether an action must be triggered. For example, when a motion sensor is tripped it tells the computer there is a tresspasser and the alarm must be triggered.

These record audio or commands from the user. For example, the amazon echo device which receives commands from the user which is sent to the computer to trigger an action.

These are useful as drawing or handwriting devices in order to input hand drawn data in programs such as photoshop.

This is a handheld or static physical device that combines a light source, scanner and decoder in order to capture information from a barcode. This reduces error from manual input of data using a device like a keyboard.

This includes Infrared touch screen which uses IR emitters to send out infrared light to travel through the glass screen to an IR receiver, when the glass is touched the receiver records less light recieved and locates the touch.

A resistive touch screen uses a glass panel covered by a thin flexible film on either side of the glass with a metallic coating that has a small electrical charge so when there is a touch both the of the metal coatings make contact which identifies the touch on the screen.

A capacitive touch screen uses a glass panel with a clear electrode layer that when toucherd transfers the electrical charge from the screen to the finger as it reacts to the bodies capacity to store electrical charge, identifiying the touch.