Many Internet users are used to downloading movies and TV series, but now there are many different services, applications, and sites where you can watch anything you want for a small fee. Some labels even roll out new releases at once on their services, and you don't have to go to the movies. But the so-called torrents have not lost their popularity. Let's find out in this material what it is, how it works, and how legal it is.

What is a torrent?

Torrent (literally "bitstream") is a peer-to-peer (P2P) network protocol designed to share files over the Internet. And a peer-to-peer network is a network where nodes "communicate" without a central element. A network protocol is a set of rules and a sequence of actions. All of this together allows devices to connect and exchange data.

Torrent files are transferred in chunks between devices (we'll refer to PCs for convenience). Each client downloads pieces of files and simultaneously distributes them to other network members. This achieves data redundancy, which reduces the dependency on each node in the network. Simply put, the same chunks of files are stored on many computers, and if some of the computers storing the files go missing from the web, the network will continue to operate.

Torrents are distributed via metadata files with the ".torrent" extension. Each file contains the required information: tracker URL, file name and size, and SHA1 control hash sums of distributed files. The file can also collect optional information: hash sums of all files and alternative sources, not by BitTorrent protocol.

How BitTorrent works. 

A client application, such as pirate bay torrent magnet, connects to the tracker specified in the file. It sends its address and the hash sum of the files it wants to download. In response, the tracker sends the client the addresses of other PCs that distribute the desired files. From time to time, the tracker sends the client new addresses of other PCs if they are available in the network.

Clients communicate with each other directly without the participation of the tracker server. The more devices store the file you need, the faster the downloading process will be since different file pieces can be downloaded from various sources simultaneously.

When connecting, clients tell each other what segments they have. The PC that wants to download the piece - it's called a listener - sends a request, and if the other PC - the sender - is ready to give, the listener gets the segment. The client then checks the checksum of the part. If it matches what is in the torrent file, the feature is successfully downloaded, and the client informs all connected that it has the segment. If the checksums differ, the piece starts downloading again. Some clients ban those peers who give out faulty components too often.

The order in which segments are exchanged is arranged so that the rarest components are distributed to clients first, thus increasing the availability of the file on the network. Parts can weigh from 16 to 4096 kilobytes.