It is a method for Net Savvies to tag, organize, store, manage, share, and search for bookmarks of resources online. These may include comments, votes for or against something, or tags that collectively.
A reasonable amount of users.
A wide ranging documentation, like a good support team
Excellent export and import features
A blog to have latest on new features
A good social bookmarking site ideally should comply with above criteria, based on these features the best social bookmarking tools according to me are as following.