With the Open Graph, your app becomes a part of the user’s identity and social graph. Through a single API, you’re able to deeply integrate into the key points of distribution on Facebook: Timeline, App Views, News Feed, and Ticker. As users interact with your app, actions are displayed on the users’ Timeline and their friends’ News Feeds and Tickers. With the Open Graph, you’ll be able to create a deep, persistent connection between you and your users, and drive new users to your app.
At Facebook's core is the social graph; people and the connections they have to everything they care about. Historically, Facebook has managed this graph and has expanded it over time as we launch new products (photos, places, etc.). In 2010, we extended the social graph, via the Open Graph protocol, to include 3rd party web sites and pages that people liked throughout the web. We are now extending the Open Graph to include arbitrary actions and objects created by 3rd party apps and enabling these apps to integrate deeply into the Facebook experience.