Have you stolen a movie today? What about music? Or maybe you’ve just exchanged some really large files with your co-workers.

The last one is legal. The first two, by simple inclusion of the word “stolen”, are not.

This is about to get heavy, my maybe-a-thieving-pirate-torrent-criminal friends, so you might like to read this before we go any further.

Ready? Here goes:

BitTorrent is perhaps the most useful piece of software to come along in about a decade. Except it isn’t a piece of software in the way most of us think; it’s what’s called a protocol. BitTorrent is a way for people to share files, and if you want to take advantage of it you need a BitTorrent client. There are many; the most popular is called µTorrent. Install it, and you can use BitTorrent to exchange files with other people.

Not a big deal in its own right. You can do that with e-mail. But what if the files is really big? E-mail won’t work. You could post the file on a server somewhere (assuming you have one), but that’s not always the best solution, because just the phrase “post it on a server” is too geeky for most people to handle. What BitTorrent does is make it so that if you and a dozen (or more) friends or co-workers each have a copy of the file on your very own computer, then when someone new needs a copy they can grab pieces of it from everyone simultaneously. It reduces problems exchanging big files by an order of magnitude, and speeds things up tremendously. If you start grabbing the file from twenty people who were available when you begin to download the file, and while you are downloading three go off-line; the other seventeen still work and pick up the slack automatically. And you don’t have to know anything. It just works.

Trading movies and music (big files!) benefit tremendously from this approach, but without commentary to whether that is the primary purpose of BitTorrent file sharing or when or under what circumstances it’s legal, it’s clear that there are legitimate uses for the technology.

The thing about BitTorrent that makes it a little bit complicated is that since any time someone downloads a file using BitTorrent, they are not actually getting the file from anyone in particular, and don’t even know where they are getting it from. Meaning that there need to be libraries describing the files and helping each computer using a BitTorrent client find participants sharing the files they’re looking for.

In a few days, when The Pirate Bay either shuts down or starts working very differently that it has until now, a VERY important library will disappear. Unless you download it and share it with the world.

Decide for yourself. Change sometimes leads to more change before people even understand it. Pay attention.