Like the social bookmarking Web 2.0 application, Delicious, Diigo allows students and teachers to bookmark web sites and categorize them with tags for future use. An Internet-based Web 2.0 application, Diigo can be accessed from any place, making it easy for students to find their saved web sites. Diigo has downloadable applilcations for smart phones, so web sites found on cell phones can be bookmarked. Diigo has a downloadable add-on that allows users to highlight, underline and annotate text on any bookmarked page. In true Web 2.0 application fashion, Diigo allows users to create networks, and Diigo groups, so sharing bookmarks and annotations is easy. This is especially nice for students working together on class projects.