From the site:
LibraryThing is not one thing. LibraryThing means different things to different people. Some use it to record what they’re reading now; some catalog every book they own. Some talk on our groups all day long, others never interact with anyone. Some share everything to Facebook, others keep their library private. Some use it for book discovery and recommendations, some to help out other book lovers with their knowledge of authors, books and series.
LibraryThing is about quality cataloging. LibraryThing started seven years ago as a way for regular people to have a professional-quality library catalog, and this is still the center for many members. We show this in our sources—searching over 700 libraries around the world. And we show it in how you can edit everything in your catalog. This isn’t just authors and titles, but every bit of data you could think of about a book, from the Dewey Decimal number and publication information to the book’s height and weight.
LibraryThing is book-geekery. We love the stuff of books—the details, the trivia, the connections among books and between books and other parts of life. We’ll tell you what percentage of your authors are dead, how much your books weigh, and whether a pile of them would be taller than Niagara Falls.
LibraryThing is about readers, not marketing. Our members like to read and talk about books, and of course we love to buy them too. But we think that reading and talking works best apart from commercial interests.
Our book recommendations are never influenced by commercial considerations.