Social bookmarking tools like Delicious and Diigo allow users to save, organize, and share web pages. Users can tag pages with keywords to describe them and then search by tag to discover related pages. Tags are a type of folksonomy that emerges from how many users describe a page. Social bookmarking provides benefits like collaboration, annotation, and accessing bookmarks from any device. It also has limitations like limited storage space and not being able to share bookmarks privately within groups on some sites. Libraries use social bookmarking for organizing resources and collaborating among staff.