Torrent

 

Torrents are a method of distributing files over the internet. They operate over the BitTorrent protocol to facilitate what’s called peer-to-peer (P2P) file-sharing.

There are a number of benefits torrent-based file sharing has over traditional file sharing. Expensive server equipment isn’t necessary to send files to many people at once, and low-bandwidth (slow) networks can just as easily download large sets of data.

The most common way to use torrents is through a special file that uses the .TORRENT file extension. Within the file are directions for how to share specific data with other people.

How Torrents Are Unique

Torrents are like other forms of downloading to your computer. However, the way in which you get the files isn’t as straightforward, and sharing your own data is much easier.

Here’s an example of how traditional file sharing works over the HTTP protocol:

1. Visit a web page in your browser.
2. Click a download link to start the download process.
3. Save the file to your computer.

The file you downloaded was on a server, probably a high-end one with lots of disk space and other system resources, designed to serve thousands or millions of people at once. The file exists on that one server only, and anyone with access to it can download it.

Torrents work a bit differently. While your web browser connects to websites using the HTTP protocol, torrents use BitTorrent, so a program that can communicate over BitTorrent is needed instead:

1. Open a torrent program.
2. Open the TORRENT file to start the download process.
3. Save the file to your computer.

In this scenario, the data you’re downloading through the torrent might exist on hundreds of servers at once, but these servers are almost always a standard personal computer in a home, just like yours. Advanced hardware isn’t required, and anyone can become a participant in this type of file exchange. In fact, anyone who downloads even a portion of the file can now operate as their own torrent server.

If you’re interested in sharing files from your computer over the internet, the traditional way to do it is by uploading the data to a central location (any file-sharing method suffices), after which the recipients can download it. With torrents, sharing is similar to saving, like described above: instead of downloading a torrent someone else made that has directions for saving their files, you share a torrent you create so that the recipients have the necessary directions to download from you.

 

How Torrents Work

This all might sound a little confusing, but the idea is actually pretty simple. Torrents, as you read above, rely on a peer-to-peer network. This just means that the torrent data, whatever it might be, can be accessed from more than one server at once. Anyone downloading the torrent gets it in bits and pieces from the other servers.

For example, imagine if I created a torrent to share a program I made. I enable the torrent and share the file online. Dozens of people are downloading it, and you’re one of them. Your torrent program will pick and choose which server to take the file from depending on who is currently sharing it and which servers have the part of the file that you currently need.

In a traditional file sharing setup that uses a file server, sharing a 200 MB program to 1,000 people would quickly exhaust all of my upload bandwidth, especially if they all requested the file at once. Torrents eliminate this problem by letting clients scrape just a little bit of the data from me, a little bit from another user, and so on until they’ve downloaded the whole file.

Once more than one person has the entire file downloaded, the original sharer can stop distributing it without it affecting anyone else. The file will remain available for any other users of that torrent because of the decentralized, P2P foundation of BitTorrent.

 

How Torrents Are Distributed

Once a torrent has been made, the creator can share one of two things: the .TORRENT file or a hash of the torrent, often called a magnet link.

A magnet link is a simple way to identify the torrent on the BitTorrent network without having to deal with a TORRENT file. It’s unique to that specific torrent, so although the link is just a string of characters, it’s just as good as having the file.

Magnet links and TORRENT files are often listed on torrent indexes, which are sites built specifically for sharing torrents. You can also share torrent information over email, text, etc.

Since magnet links and TORRENT files are just the instructions for a BitTorrent client to understand how to get the data, sharing them is quick and easy.

A torrent file isn’t super useful unless it’s used with a client program. Here’s an example of a torrent open in a text editor—you can see just how pointless viewing the torrent in this way is.

Common Torrent Terms

Here are some helpful terms to know when dealing with torrents:

• Seed: To seed a torrent is to share it. A torrent’s seed count is the number of people sharing the full file. Zero seeds mean nobody can download the entire file.
• Peer: A peer is someone downloading the file from a seeder, but who doesn’t yet have the full file.
• Leech: Leechers download more than they upload. A leecher might instead upload nothing at all after the full file has been downloaded.
• Swarm: A group of people downloading and sharing the same torrent.
• Tracker: A server that tracks all the connected users and helps them find each other.
• Client: The program or web service used by a torrent file or magnet link to understand how to download or upload files.