If you ever wonder "How Torrents Work?"

The concept is peer to peer sharing of files(like online sharing of files).A person shares the file he has by using a torrent client (a software which downloads the original file you wanted") and you download the file using the same class of software.concepts include "seeding" and "leeching".

you start with downloading a .torrent file.This file is a small file which your client uses to know where the real download file is located and manages and downloads the original file for you.

the original file from a "seeder" (People who have the complete file) is broken into N pieces and distributed among the "leechers" (the one who are downloading the file) like us who are trying to download,without redundancy.so you download one 1 piece at a time to complete the file.once you complete your download (i.e you have the total N pieces of the file => you have the complete file) you become a "seeder" and you seed the file for other "leechers".this goes on and on....
Please refer to the concepts given below to understand.

Seeding

The user who first uploaded the file or files in question acts as the first "seeder." A seeder is a user who is in possession of the completed file and has made it available for others to download. Users in search of the file connect to as many different seeders as possible at one time and download pieces of the completed file. Because only part of the file is being downloaded from many different users, this greatly improves the rate at which a person can download a file. It also relieves bandwidth and hardware use for the originator of the file.

Leeching

People who have only a partially completed version of the file in question are called "leechers." These people are also uploading whatever parts of a file they have at the same time as they are downloading the remainder. This process improves download rates for everyone involved, as the more seeders and leechers a user connects to, the more parts of a file they can download at once, which means the file will finish downloading faster. When a user is down downloading a file, they themselves become seeders for others to download from.