The term "car audio" is an umbrella term describing the sound system fitted to an automobile. Somewhat different but quite similar is the "stock car audio system," which refers to a system specified by the manufacturer when the car rolled off the assembly lines. At its extremes, the installation of custom car audio can involve anything from the upgrade of a radio to the radical full-blown customization of a vehicle around its audio equipment to include features such as car stereo CD changers.

Most widely used audio equipments are the radio/tape/CD/DVD Player which usually described as a Head unit. Recent developments in head units technology are the addition of CD players with WMA, MP3, AAC, USB, Bluetooth and Wi-Fi support integrated.

Today most of the cars come with at least a CD player / CD recorder, and some come with option for a car stereo CD changers able to hold multiple disks in the head unit itself or in a separate unit located in a trunk or console. Today main type of CD changers can be categorised into External Cartridge, Internal Cartridge and Carousel CD changers.

Stereophonic sound is commonly referred to as stereo and it is the reproduction of sound wherein two or more andependent audio channels are used to create the same effect as hearing natural sound heard from different directions, same as that heard in natural hearing. Car audio stereos usually employ 2-channel sound recording and sound reproduction using data for more than one speaker at the same time.

During the time of mono radio, the most common speaker location was in the middle of the dashboard pointing through perforations towards the front windshield. With the advent of stereo system, car audio speakers are located in doors and rear parcel shelves in modern cars. High-end or competition stereo systems like car stereo CD changers have speakers mounted in kick panel enclosures, allowing for larger drivers and better driver placement.

The amplifiers are used to drive the speakers. These provide the necessary music power, which is measured in watts. An amplifier is a very important component of good car audio speakers system. One should always ensure that the total power handling capacity of the speakers connected to the amplifier or head unit is greater than the power of the amplifier or head unit.