Input and output devices allow users to interact with and control computers. Common input devices include keyboards, mice, joysticks, light pens, trackballs, and scanners. Output devices convert computer information into human-perceptible forms like text, graphics, audio, and video. Examples of output devices are monitors, printers, plotters, projectors, speakers, and headphones. Monitors display processed data while printers create hard copies. Projectors magnify computer output onto screens for presentations. Speakers and headphones output audio information.