BookMooch: a community for exchanging used books

A website that recently appeared can be used to exchange old books. The procedure is very simple: list the books you no longer want on the site, and if someone needs them, you send the book to them, and in return, you receive one point. When you find an old book you like, you can use this point to exchange for someone else's old book. The shipping cost of sending the book is borne by the owner of the old book. Essentially, it is a mutually beneficial activity because when others send you a book, they also have to bear the shipping cost. Hehe, all books are equal in value, each worth one point. However, such a setting has its own rationality. The same book has different values in the eyes of different people. Exchanging allows both parties to obtain the books they like.