The passing of information into or out of the processing unit of a computer. Input devices include keyboards, pointing devices such as the mouse, document scanners, magnetic-card readers, and speech-recognition units. The most common output devices are printers and visual displays. Magnetic disks and magnetic tape are examples of media used for the recording and reading of data. An important function of most I/O equipment is the translation between the processor’s signals and the symbols, actions, or sounds understood or generated by people.