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Of course. You can read the protocol specification and/or study the source code of the existing libraries and clients to figure out how they work.

I think a reasonable first step is learning about B-encoding so that you can parse and generate torrent files.

Here is a bit torrent client I wrote back when I was in school. https://github.com/war1025/Torrent

How do you think Bt or libbittorent was written?

I was thinking about this kind of DIY short term effort to have an example of torrent functionality. Not collaborative development of a torrent library for 10 years.