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http://www.paperbackswap.com/help/search.php?terms=tag < here is the help center document about tags. I'll tell you a quick run down. Tags are like adding a note about the book. It can be anything from the main character of the book to setting or what series its from. You can also make a personal tag. Like some people tag all the books on their wish list so they can tell when they are searching if they have added that book.