In case you've been living in a post-Y2K bunker, a few details: Napster is a very simple program that "reads" the MP3 music files on your hard disk, then publishes this list to a server somewhere out on the net.  Everyone using Napster publishes to a common database, which you can then search to find any title you might be interested in. Napster displays a list of matches -- nearly every popular song from the past 40 years can be found -- then you click on an item, connect to another Napster user, and get the file directly from them.  Napster is just a clearinghouse, a way-station on the road to tunes.

This database is in constant flux; it all depends upon who is using Napster right now. Songs come and go. So eternal vigilance is the price of a good collection of MP3s. (I have been very vigilant, snagging over 1 GB of MP3s in less than two weeks.)

The RIAA has a less charitable view:

     Napster is similar to a giant online pirate bazaar: users log onto Napster servers and make their previously
     personal MP3 collections available for download by other Napster users who are logged on at the same time.
     Napster provides its users with all the facilities and means to engage in massive copyright infringement. For
     example, Napster provides users with a hub of central computer servers to which they connect; a continuously
     updated database of "links" to millions of pirated recordings; software that allows fast, efficient identification,
     copying and distribution of the pirated recordings; and a host of other services -- all of which enable and
     encourage Napster users to download millions of pirated songs as well as make available their own music library
     for others to copy. Because Napster creates its links from the personal MP3 collections of Napster users, without
     Napster, these infringements would not be taking place at all.