Like other backlink strategies, social bookmarking is a way to generate traffic and having backlinks to promote the site. Submission to good bookmarking websites like StumbleUpon, Digg, Reddit, Delicious, etc. permits members to promote a site’s content in various manners like bookmarking, voting, liking, etc. Sometimes bookmarking sites provides do follow link to boost up Page rank and search result ranking.
Social bookmarking also alerts people about your online present providing direct link to your site’s content. Furthermore search engines use to use their links to evaluate a web page’s search ranking. As it is completely in your hand you can promote site without worrying about backlinks.