Library Thing is a free online cataloging tool and social networking site that allows users to catalog their personal book collections and connect with others. It also offers paid plans for libraries to integrate the tool's features, like crowdsourced reviews and tags, into their own catalogs. The document outlines how libraries can use Library Thing by having staff and patrons create free accounts to catalog books, write reviews, start discussion groups, and connect it with the library's website and mobile app for a more engaging online experience.