"Social signals are one of the most notable addition to Google’s search ranking factors this year, as it is a strong indication of user activity or behavior on pages all across the web.
These signals are basically retrieved from popular social networks such as Facebook, Twitter and perhaps soon via Google +1, determining pages that receive a lot of attention and social popularity in order to be returned as results to relevant search queries.
The main principle of Google and Bing in using these signals is to locate fresh, relevant and significant materials over the web (news, resource, etc) through viral sharing and natural prominence".
However, these search engines do have factors to consider in measuring the durability of the content, for them to truly return quality sites on their end such as:
1) Quantity of social mentions on Twitter and/or Facebook.
2) Quality of social mentions measured through the social authority of the Twitter account.
3) Domain authority and Trustrank of the site hosting the content
Full Article Here: http://kaiserthesage.com/social-signals/
Via Antonino Militello