Torrent

A torrent file acts like a table of contents (index) that allows computers to find information through the use of a Bittorrent client. With the help of a torrent file, one can download small parts of the original file from computers that have already downloaded it. These “peers” allow for downloading of the file in addition to, or in place of, the primary server.

Torrents files are normally named with the extension “.torrents”.

Torrents files themselves and the method of using torrent files have been created to ease the load on central servers, as instead of sending a file for request, it can crowd-source the bandwidth needed for the file transfer, and reduce the time needed to download large files.

Many free/freeware programs and operating systems, such as the various Linux distributions offer a torrent download option for users seeking the aforementioned benefits. Other large downloads, such as media files, are often torrented as well.

Typically, Internet access is asymmetrical, supporting greater download speeds than upload speeds, limiting the bandwidth of each download, and sometimes enforcing bandwidth caps and periods where systems are not accessible.

This creates inefficiency when many people want to obtain the same set of files from a single source; the source must always be online and must have massive outbound bandwidth. The BitTorrent protocol addresses this by decentralizing the distribution, leveraging the ability of people to network “peer-to-peer”, among themselves.

Each file to be distributed is divided into small information chunks called pieces. Downloading peers achieve high download speeds by requesting multiple pieces from different computers simultaneously in the swarm.

Once obtained, these pieces are usually immediately made available for download by others in the swarm. In this way, the burden on the network is spread among the downloaders, rather than concentrating at a central distribution hub or cluster.

As long as all the pieces are available, peers (downloaders and uploaders) can come and go; no one peer needs to have all the chunks or to even stay connected to the swarm in order for distribution to continue among the other peers.