There are basically 3 types of inputs these days;

1. iPod input, which allows you to actually control the iPod from the head unit. This option is normally mounted into the glove box or centre console (or sometimes on a dock in the dash if you feel the need). Great option if you have an iPod with a decent music collection.

2. AUX input. Simply a line in, you can connect anything with a headphone jack. You will still need to control your music from whatever device you are using.

3. USB/Memory card. Plays MP3's off the device, just like using an MP3 CD, only slightly easier.


In most cases I suggest getting an iPod hookup if you already have an iPod, otherwise look at something that uses flash memory. The LineIn option just doesn't do it for me.