Not too long ago there weren't that many choices for how you played music on your car audio system. In the early 1970's when car audio first became available, an 8-track was about it, unless you carried around a portable record player. The bulky 8-track was soon supplanted by the cassette - but at least you could have a picture of the album cover on the former.
As technology changed small and recordable cassette tapes became the standard. Cassettes were convenient and easy to store and had up to two hours of space available. Moreover home recorders were cheap, unlike home 8-track recording machines. But what really helped launch the cassette tape was portability. The Sony Walkman practically re-created a whole genre in music formats.
Cassette players were the only thing car audio head units came with for a solid ten years before the first CD players hit the market. These were slow to come; they were expensive and didn't even have tuners in them. You had to connect them to your existing radio; or else, all you had was a CD for in car entertainment.
Leap forward to 2001 and the choices today are astounding. CD is still king and it will continue to be for quite some time because it's a great format, but some of the newbies are really going to change the landscape. Today you can play CD, DVD, cassette tape (they do still sell them!) or connect a portable MP3 player to your system. And another format is coming that's really portable. If it's not available by this summer, it will be for 2002. That's a memory card or chip.
Today memory chips are used in digital cameras and portable MP3 players; even Rockford Fosgate's new MP3 changer uses memory chips. Sony has the Memory Stick, Panasonic has SD for Secure Disk (though it's a chip) and there are a lot of generic versions like the ones used in digital cameras. The chip format is going to really explode soon because it is the ultimate in portability. Think about it - it won't skip, there's nothing to wear out, magnetic sources don't erase it, it's extremely durable so you can drop it without a care, and it's super small.
There are, however, a couple of hurdles in getting memory chip based products to the masses today. The first is protection: the kind the music industry wants. They know they have a good thing going and they don't want to lose it, so they don't want anyone to make more than one copy of anything that is digital.
With a cassette tape when you make a copy of a copy of a copy, you quickly start to lose the integrity of the original. But with digital, you can keep making copies and the last sounds as good as the first. However, you can already make a copy of your CD music with a CD-R on your computer or even a home CD burner. That burns the music execs and they have found ways to make sure a home CD burner won't copy a copy.
But the real thorn in their side is the Internet. When you make a copy of a CD at home, you have already bought a CD and the studios have received their cut. But with the Internet, you can get a copy of nearly any song for free. With Napster people are getting entire albums for nothing - and the distribution is massive. At home it's you and your friend, while with Napster, it's you and 10 million strangers. So you can see the music industry's point. By the way, it is illegal to copy any piece of copyrighted music for any other use than your own. Just thought you should know.
Actually it's tough to figure about why industry executives are so worried; the MP3 format off the Web is lo-fi. By its nature, MP3 doesn't sound nearly as good as the original recording; that's how they get so much information into a small file that's easy to transfer on the Internet. So until the number crunching nerds get an new way to make a compressed MP3 file sound as good as the original, the music guys shouldn't worry too much.