The keyboard is the most common input device. A scanner or video camera can deliver information and images to a computer. The computer then interprets and carries out instructions, receives, sends, and stores information using circuit boards. Computers store the programs and files in their memory. Disks store information in magnetic patterns which can be used to manipulate electric current.
Output is the text, picture, graph or sound that is returned after it is processed.
The visual monitor is the most common output device. A printer puts information onto paper. Finally, computers need software. Software or computer programs are lists of instructions written by a person that tell a computer what to do. Software is stored as a set of electromagnetic code signals in the computer's memory, on a disk or microchip.