Long story short, BitTorrent is a way for you to access all kinds of information on the Internet just by using a file sharing program. All sorts of multimedia, legitimate or illegitimate, can be accessed by pointing your web browser to the right URL. But before we can ponder what a BitTorrent client is, we need to discuss what BitTorrent does, and delve into a little bit of internet downloading history.

In the Beginning, There Was FTP

Long before BitTorrent, before Napster (remember that?), and even before the world wide web, very smart people—people smart enough to invent the internet—needed a way to get files from one computer to another without having to resort to floppy disks (remember those?). So they came up with "file transfer protocol," or FTP.

People in one location could set up a FTP server—a machine on the internet that serves as a centralized location for storing files—and people at other locations, on various computers, could connect to that FTP server. The people at these remote locations are able to download whatever files are made available—in those days it was exciting stuff like RFCs and databases—to the local computer (the FTP server).

The problem with FTP is what's sometimes referred to as the bottleneck effect. A bottleneck, in the world of data transmission, happens when you have too many clients downloading from the server (centralized) all at one time, causing the transmission of the data to slow down or even stop. Why does this happen? Because the server can only chug out so much information at once before choking to death.

Another weakness of FTP is the complexity of the client; often you have to type in commands or know about stuff like directory trees and sub-directories (er ... folders and sub-folders).

Along Came Napster and Sat Down Beside Her

In 1999, peer-to-peer (P2P) became all the rage. The program, called Napster, brought the idea of file sharing to the masses, not just those with access to their university’s FTP server.

Decentralization was the word, meaning one person could share one file to 10,000 of his closest friends and the P2P program could look on the Napster server, find out which peers had that file, and download it from any number of peers out there who had it.

Then Metallica and Dr. Dre decided that they didn’t like all that free advertisement and sued Napster, which then disappeared only to be replaced by the whack-a-mole P2P protocol du jour, each new protocol more decentralized than the last.

BitTorrent Isn’t the First, and It Sure Ain’t the Last

Back in the days of FTP, the roles of client and server were pretty concrete: you use a client program to access the server somewhere out there in Internetland. With P2P, things become a little hazy where the concept of server is concerned because you may be downloading little bits of the same file from multiple sources, but the client remains the same.

Here’s how it works: with your web browser (Firefox, right? because you wouldn't want to put your computer at risk by using Microsoft Internet Explorer, would you?) you download a .torrent file. This file contains the description of what’s being shared—you know, like a Linux distribution’s .iso file. You then feed this torrent file into your BitTorrent client, which contacts the “tracker,” which then directs the client to where the actual, "physical" file(s) can be found.

One of the ideas behind BitTorrent is that once you’re done downloading the file, you help to keep the torrent going by being a “seeder”—that is, letting others who join the torrent access the physical file on your local computer. The more seeders, the better, and keeping the torrent going as long as possible makes you a good citizen when it comes to BitTorrent, unless you're sharing your music collection, then that makes you a bad citizen according to "law enforcement."

The BitTorrent protocol is the latest in file sharing tech, and promises to be for some time. And since it’s open source, people can look at it, make it better, or build better clients with all sorts of bells and whistles.