 If you've downloaded a TV show or a movie without paying for it in the last few years, you've probably used a torrent. They're one of the major ways to transfer files, making up as much as half of all internet traffic by some estimates. They're a big deal, and while it can seem like torrenting is just downloading a file directly from the web, the reality is a lot more interesting. Just to keep things legal, let's say you're looking for the complete works of Shakespeare. It starts with a torrent file, usually named after whatever you're downloading. That's not the full package, though, it just lets your computer know what it's looking for. To download that file, you need a client, something like uTorrent or Transmission, which manages the download and assembles the file. Assembling that file is really complicated work. When it becomes a torrent, your file gets broken down into thousands of tiny snippets, and the torrent file lets you know where to find each one. One might be on a computer in Singapore, another in Brazil, but the client lets you download all of them separately and reassemble them on your computer. And once each chunk of data is safely on your computer, you start sending it out again, sharing the parts of the file you have while you look for the ones you don't. To figure out where to get those snippets, you need a tracking system, typically a server that's specified in the initial torrent file. It keeps track of who's got which snippets, giving you a real-time map of where all the different parts of the file are. There are a couple technical benefits to this. Unlike direct downloads, a single torrent can serve tens of thousands of people without any significant load on the tracking server. If a few nodes go down, the network doesn't really care. It turns out to be a really robust way to distribute big files across a lot of far-flung computers. But if we're honest, that's not the real reason to get files this way. The real reason is you're stealing things, and you don't want to get caught. If a single person were hosting the file, that would be the first person the lawyers would go after. And back when people were using Napster and SoulSeek, that's exactly what happened. But now, when they want to pull the same move on a popular torrent, they have to go after ten thousand people at once. It still happens, but it's a lot harder for content owners, and it doesn't happen nearly as much. They can also go after the tracking servers, like they did with the Pirate Bay, but systems like magnet links mean you don't always necessarily need a tracking server. It's the result of a twenty-year arms race between pirates and the entertainment industry. And at least for right now, it's still kind of a free-for-all.