Social bookmarking site enables you store bookmarks, add tags of your choice, and designate individual bookmarks as public or private. Bookmarking site notify the user when the URL no longer functions. In a social bookmarking system, users save links to web pages that they want to remember and/or share. Social bookmarks are public, and can be saved privately, shared only with specified people or groups, shared only inside certain networks, or another combination of public and private domains.