Many people would like to listen to the music that is on their iPhone while in their car, but become frustrated because it's often not simple. If you are very lucky, your car already came with an iPhone or iPod kit that includes a dock connector that hooks up directly to your phone. Then, the music will play through your car speakers. In some cases, you control the music with the iPhone itself, and in other cases your car will provide an alternative interface which is meant to be safer to use while driving. Most cars do not have this kind of iPhone integration. It's worth asking at your car dealer if this option is possible for your car. In most cases, this will be quite expensive. Another option is the auxiliary input on your car stereo: Many stereos have the ability to intake an audio signal from another device such as your iPhone. This will probably mean a common and inexpensive mini RCA cord that connects to the headphone jack of your iPhone and the auxiliary input port on the car stereo.

If neither of these options are possible, you can investigate a radio transmitter. Essentially this is a small device that will take the audio output from your iPhone and transmit it over a certain radio frequency. Then, you can tune your car radio to that particular station and listen to your music! This sounds like a crazy approach but it actually works fine. The downsides are that you need to use an extra device and that the sound quality may not be great.