The document discusses Diigo, a social bookmarking tool. It provides an overview of Diigo's features including bookmarking and tagging web pages, highlighting text, adding sticky notes, reading pages later, and filtering bookmarks. It describes how to use the Diigo toolbar and create student and teacher accounts to allow for classroom collaboration and sharing of bookmarks and annotations. Premium features like caching pages, capturing screenshots, and full-text search are also mentioned. The document encourages using Diigo's community features like groups, networks, and forums to share ideas and questions.