A processing device is any component in a computer that manages the storage and retrieval of information. Typical examples of processing devices include central-processing units, computer motherboards, network cards, graphics-processing units and sound cards.
Computers are fed data, process that data with codes and produce results. Data is entered into a computer via input devices, including a keyboard or mouse. This data is processed into information and then output on such components as monitors or sets of speakers. The data received from an input device first goes through an intermediate stage before being output on appropriate devices. The CPU, for instance, takes entered data and performs necessary processing, including calculations, and saves it on the computer's memory.