A head unit is a component of a stereo system either in a vehicle or home cinema system which provides a unified hardware interface for the various components of an electronic media system. An antiquated name for a head unit is a receiver ; this article focuses on vehicular applications.
The head unit is the centerpiece of the car's sound system. Typically located in the center of the dashboard, modern head units are densely integrated electronic packages housed in detachable face plates. As high-end head units are not uncommon targets for theft, many head units are typically integrated into the vehicles's alarm system.
Head units give the user control over the vehicle's entertainment media: AM/FM radio, satellite radio, CDs, cassette tapes (although these are now uncommon), MP3, GPS navigation, Bluetooth, etc. Many audio-only head units afford the user precise control overetailed audio functions such as volume, band, frequency, speaker balance, speaker fade, bass, treble, EQ and so on.
Several OEM manufacturers such as General Motors are integrating computer systems into vehicle's head units such that they can control vehicular functions such as door chimes and even offer vehicle data such as trouble warnings and odometer information; such a head unit thus serves as a secondary instrument panel.
Inasmuch as head units are a central part of a car's decor, they vary as widely in aesthetics as they do in functionality; in this regard they are analogous to skins. With the advent of GPS and DVDs head units with video monitors have come on the market. Such features raise design, safety, and ergonomic issues.
The most standard sizes in vehicles are Single DIN ISO 7736 (178x53mm) in Europe, South America and Australasia and Double DIN (178x106mm) in Japan and North America.
Typically, the 8-pin ISO 10487 connector is used for connecting the head unit to the car's electrical system
