Well, think of it as a road map of the web, commended by people who have traveled it at length. 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 or collaboratively become a folksonomy.
What features to look for?
A reasonable amount of users.
A wide ranging documentation, like FAQ’s and 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.
StumbleUpon, ranked 116th in web traffic is among the best social bookmarking tools and can be a great tool to generate traffic to your web site. At StumbleUpon is you are able to take advantage of a huge network of dedicated web searchers who are sharing their experiences with you. StumbleUpon is definitely an extremely addicting way to search the internet because the caliber of the sites is simply so awesome.
At reddit users can create communities called “subreddits”, which share common interests. Most popular examples are Pics, Programming, Science, Politics, Gaming and AskReddit. Ranked 138th in terms of web traffic, reddit is one of the best social bookmarking tools.
Digg is ranked 139th according to Alexa.com in terms of web traffic with an estimated 8.5 million U.S unique visits per month, its rank in U.S is 96. In May 2009, Digg launched a new feature integrating Facebook Connect with Digg which allows users of Digg and Facebook to connect their accounts. Users can share their Digg articles on their Facebook page when connected to a Facebook account.
Delicious (Formerly Del.icio.us)
This is by far the most popular, though not most powerful social bookmarking tool. It does not offer very powerful tools for sharing but the size of the community makes the experience great fun. By the end of 2008, the service claimed more than 5.3 million users and 180 million unique bookmarked URLs. It has flourished in repute after being acquired by Yahoo.
Diigo is being considered the newest favorite web tool. Besides saving your favorite internet bookmarks, putting sticky notes online and posting comments, it allows users to highlight any part of a webpage, attach sticky notes to specific highlights or to a whole page.