Filesharing titan the Pirate Bay has promised to remove all .torrent files from its site. But it's not to placate rights-holders—it's going to replace them with "magnet links" instead.

Back in 2009, the Pirate Bay shut down its tracker—a server that helps people who want a file to find a person who has it. While a tracker doesn't actually host any files, operating one for the purposes of helping people share copyrighted content has generally been found to break the law in the countries where cases have gone to court.

Trackers have largely been made redundant by magnet links—which allow for so-called "trackerless" torrents. Originally, BitTorrent users would download a .torrent file which, when opened in your BitTorrent software on your computer, calculates a "torrent hash" that identifies the files required. The software then sends that hash to a server, and connects to people who have the files that you want. They then download.

Magnet links differ by making the torrent hash calculation on the server, sending that data within the link itself. In the same way that opening a link to a Spotify track sends that data to Spotify, a magnet link sends the relevant data to your BitTorrent client, so that the download can begin.

The other function that a tracker provides is helping people find other people that are downloading the same files, so that they can share completed chunks of those files. That role has been superceded by technologies like DHT and Peer Exchange (PEX), which share information on who is downloading what over the network. Instead of asking a central server who has what file, you ask the people you're already downloading from, who ask the people they're downloading from, and so on.

The downside is that it can take a little longer for downloads to "get going," but the network effect means that this information can generally be found very quickly, especially for popular files. If you're curious, TorrentFreak has a good explanation of exactly how it all works at a deep technical level.

The development of these technologies means that .torrent files are pretty redundant now. As such, while the Pirate Bay has offered magnet links for some time, the site has now made them the default option for downloading. In a month's time, the .torrent links will be removed entirely.

That has side benefits, too. It shrinks the size of the Pirate Bay massively—allowing copies of the site to be hosted with significantly less bandwidth, so that it's even harder to shut down. It's even feasible that you could carry a copy of the site on a USB stick.

It's worth noting that .torrent files will never disappear entirely. One person needs to use a .torrent for each new file to inject crucial information about a download into the "swarm" of people downloading. For most practical purposes, though, and for most users, they'll soon become a thing of the past.