The document discusses Facebook's Open Graph, which allows websites and apps to personalize content for users based on their Facebook profile information and activity, even if they have not visited the site before. It shares what information is shared, such as pages and people a user likes. It provides examples of how Pandora and Yelp can personalize experiences based on Facebook likes. The Open Graph enables a more personalized and social web experience across different sites through the use of plugins and APIs.