A torrent is a computer file(1) that contains information about a specific and usually large or even very large file(2).
File(1) is used by a torrent (computer) program to seek, find, and download parts of file(2) until all parts are downloaded.
For example, let's say that someone videotapes a shocking or amazing event. The video file is digitized so that computers can read it. Then a torrent is created for that file. People download the torrent and run it in their torrent program to download parts of the initial video file until they have the complete file.
At first this takes long as only so many people can access that first file (let's say 5 people at first).
After the first file has been downloaded there are now 6 people sharing that file (1 + 5) and each of them shares with 5* people. Now 30 more people can download that file (6 x 5).
Moving right along, there are now 36 people sharing so 180 people can download .... then 216 sharing .... then 1,296 ...... etc, etc.
Pretty soon there are hundreds of thousands or even millions of people sharing that file, so it is easy for everyone to share it because they only have to share a little piece of that file.
The torrent contains info that tells the torrent program which parts of the file to look for so that it can find and download all parts of the file from different computers around the world until it too has the complete file and can also start sharing.
Some people just download and don't share, but those who do share allow their torrent programs to re-create that initial torrent so that they are part of the sharing process. Once they have re-created that initial torrent, people can now download from them.
This whole sharing process is referred to as a P2P (peer to peer) sharing protocol (network). The network includes anyone with a computer who has downloaded a file and used their torrent program to continue sharing.
..... did I make this as clear as mud?
* The number 5 would actually increase each time that the file was shared because more people are sharing, but I didn't want to get into the whole exponential thing during this response.