system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is a torrent?
gpt
Imagine a big computer file is like a giant book. Suppose the only way you could get a copy of the book from a single person was one page at a time. Well, it might take too long for you to wait to get the book from just one person. How can you speed it up? You could get pages from many people at once. But how to keep track of what you need?

What if it was a copy of the book with a table of contents and a bunch of chapters. If you want a copy of the book first ask one person for the table of contents. Once you have the table of contents, you can call out all the chapters do you not have. Anyone what has those chapters can start giving you the pages of the chapter.

These people do not even need to have the whole book, they only need to have one of the chapters you need. This works really well if a bunch of people are trying to get a copy of one book. The person with the complete copy first gives everyone a table of contents and a different chapter. Everyone starts yelling out what chapters they need and everyone works together sharing chapters until everyone has a copy of the book.

tl;dr A computer file is treated like a book with a table of contents and chapters.