Social bookmarking provides a means of sharing references to Internet sites and organising your bookmarks. Using a social bookmarking system your bookmarks to web sites and resources are saved on the system and accessible to you and others via the Internet (though you can make them private if you wish). This social element is important as it means you can look at the bookmarks of other users, carry out subject searches on their links and share links by email or through the use of common tags (metadata).
There are many social bookmarking systems available, for example Delicious, Diigo, Stumbleupon and Citeulike.
Getting started with social bookmarking