An FM Transmitter is a portable device which is plugged into a headphone jack of a portable audio or video device and thereafter the sound is transmitted through a broadcast frequency. The main purpose of using an FM transmitter is to play music through a car stereo or any other radio. They generally operate on battery and need to be charged on a regular basis. However, off late they have also been developed to work on cigarette lighter sockets too. FM Transmitters play good quality music in a limited environment and have good quality display as well. Main devices to transmit audio from are MP3 and CD players as they can be easily carried around and heard at a decent sound level.