system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 torrents

I think I understand it but i'm not sure.
gpt
You want a new book that has 100 pages but don't actually want to purchase the whole thing, so you go to a meeting place (tracker) where everyone who has the book or who is interested in getting it all get together.

Then, you tell everybody that you are looking for pages 1 to 100. People start making copies of random pages from their own books and give them to you. You will received them out of order, but it doesn't really matter since the page number is at the bottom, so you can easily put them back in order.
After a while, you have a small stack of pages yourself and can start sending pages even if you don't have the full book.

Leechers are people who don't have the full book.
Seeders are people who do have the full book. They won't ask for pages.

One seeder is enough for a whole group of people. For exemple, as soon as the seeder has sent a page to someone, both of them now have the page and they can both start making copies for other people.

The strength of torrents is that:
1. You can start sharing even if you don't have the full file.
2. You can receive the file out of order.
3. Everything is checked in real time so that if you receive a corrupted page, it is discarded and requested from someone else.

The main disadvantages are:
1. The file comes in out of order. For a video file, for example, you will have to wait until you have the whole thing before you can watch it.
2. People have to share. Otherwise, it's the same thing as normal P2P software.