Overview
The term Social Graph was originally coined by scientists working in the social areas of graph theory to describe the global mapping of people and how they’re related to each other. Social Graph has since been expanded to refer to the mapping of relationships of all Internet users.
Benefits of the Social Graph
Users
Navigating the web will be a better experience for users because they will be able to see peer recommendations from articles to products.
Companies
Companies can utilize the information made public to target their visitors with personalized recommendations and offers.

Social Graph Examples
Google +1
Google jumped into the social arena by introducing the +1 button in March of 2011.
Facebook Social Plugins
Facebook rolled out their social plugins in 2007 at the Facebook f8 conference.