Del.icio.us is a social bookmarking site founded by Joshua Schachter in 2003.  The site, which was purchased by Yahoo in 2005, features 100 million bookmarked URLs and three million users.  Delicious utilizes tags very prominently.  Users “tag” their bookmarks with keywords that describe them.  For example, a bookmark of a web site that provides math help might be tagged “math,” “geometry,” and “trigonometry.”  Then when someone wanted to find sites pertaining to geometry and they searched for the tag “geometry,” your bookmark would appear in the listings.  Del.icio.us describes tags on their home page as: “simply a word you use to describe a bookmark. Unlike folders, you make up tags when you need them and you can use as many as you like. The result is a better way to organize your bookmarks and a great way to discover interesting things on the Web.”  Finally, Del.icio.us provides lists of the most popular bookmarks.  Del.icio.us makes your bookmarks portable by housing them on the web and allows you to share them with your friends and the internet community at large.