Napster sold out a long time ago. Kazaa is loaded with spyware. But BitTorrent is the future.

BitTorrent (available at www.bittorrent.com) represents a brilliant new solution to a problem familiar to anyone knowledgeable about peer-to-peer (P2P) applications: how to best distribute a file (think LEGAL pictures, applications, research data sets, PDFs) to many people as quickly as possible.

This process is limited by the number of machines, or "peers," that have the file, as well as the bandwidth available to deliver it. If you've ever spent an entire weekend downloading a movie at speeds around one or two kilobits per second (kbps,) you've seen the effects of these limitations first-hand.

To understand how BitTorrent works, it's best to compare it with Kazaa, arguably its most popular antecedent. After you search on Kazaa, you are presented with a list of results, and you can choose to download the file from a particular "host," or computer that already has the file.

The problem here is uploading. The speed at which you download can never be faster than the rate at which the host uploads -- and unfortunately, many broadband providers support upload speeds of only 10 percent of download speeds. Think of this "one-to-one" transfer like writing a letter to a single person.

BitTorrent is more like broadcasting a file to the entire world. To start, you download a "torrent" file from a Web site (the legality of all this is questionable; I'll leave the detective work of finding these Web sites to you) and then open it using the BitTorrent application.

The first few minutes of downloading are thoroughly unimpressive. But then something magical happens. (I use "magical" in the thoroughly geeky sense of the term, like calling 802.11g "hot.")

As soon as you open the torrent file, your computer begins searching for other people on the Internet who have the file you're looking for. Then, you download a small chunk of it from many people simultaneously, which means it usually comes across very quickly.

As soon as you have the small chunk, you begin to upload it out to other people who are looking for it, and a cycle begins: The more popular a file is, the more people have it, meaning more people upload it, which means people can download faster, which makes it even more popular.

Your downloads start off slowly but grow exponentially. I just finished downloading a file at average speeds of around 250 kilobits, which, in case you don't know, is pretty damn fast, especially if you're accustomed to the Kazaa architecture. So the name "BitTorrent" couldn't be any more accurate.

BitTorrent is revolutionary in ways that go beyond its protocol design. It's an ideal way to download TV shows, for example. Rarely anymore do I watch a TV show while it's actually airing. It's far more convenient for me to download the torrent file (which can sometimes appear as little as one hour after the show airs) and watch it at my leisure later, with the commercials already stripped out for me.

If that sounds a bit like TiVo, you're right -- but BitTorrent can beat even this.

BitTorrent is particularly well designed for taking a file that might traditionally have lingered in obscurity on somebody's computer and instantly make it available to millions of people. Wired Magazine cited Jon Stewart's now infamous appearance on CNN's Crossfire as an example of BitTorrent's power: Although only about 867,000 people saw the name-calling on TV, millions saw it online over the next few days.

Not unlike blogs, BitTorrent is having a powerful effect on traditional media, and the most liberating part (or the scariest, depending on your point of view) is that there are very few ways to stop it.

Groups such as the Motion Picture Association of America have already forced the shutting down of formerly popular torrent sites such as SuprNova.org and TorrentBits.org. These sites provided organized, searchable catalogs of torrent files, thus making it tremendously easy to find what you're looking for. For every site that's taken down, though, another will grow to take its place.

BitTorrent's popularity has been growing at the same exponential rates as the downloads it offers, so much so that I'm not sure if this column will be cutting-edge or passé by the time it is printed. So no matter what cult favorite video clip, audio file or picture you're looking for, you might want to give BitTorrent a try.