Input devices are pieces of computer hardware used to provide data and control signals to computers and other electronic devices. Some common types of input devices include keyboards, mice, joysticks, light pens, trackballs, and scanners. Keyboards are used to input text and commands and are an important output device. Mice detect two-dimensional motion relative to a surface and translate that motion to pointer movement on a display. Joysticks report the angle or direction of a pivoting stick. Light pens are light-sensitive wands used with CRT displays. Trackballs contain sensors to detect the rotation of an exposed ball, similar to an upside-down mouse. Scanners capture images from physical sources for computer display and editing.