Whenever you want to bring engagement and growth on your web site you can use Facebook’s strong APIs to create social experiences and place your web site into the spotlight. With Facebook API get people and the connections they have and nest plans for future enlargement. Integrate with the social graph to drive registration, personalization, and traffic thanks to the Facebook Platform and the containing set of APIs and tools. Whenever needed you can get started with Facebook for: websites, applications on Facebook.com and Mobile applications.
Take a look over some of Facebook's API details:
The core of Facebook Platform or the Graph API is the one that allows you to read and write data on Facebook. The Graph API offers a simple consistent view of the social graph, representing objects such as people, photos, events and pages but also the relations between them such as likes, photo tags and friendships.
Facebook Platform allows you to connect with social channels like the: News Feed and Requests to aid you drive growth and engagement for your web page, application or content.
Facebook authentication allows your app to get-in-touch with the Graph API on behalf of the Facebook users, offering a strong single-sign on different systems over Web, mobile and desktop applications.
Just with a line of HTML, social plugins allows you to offer amazing social experiences to your users. The content is personalized to the viewer whether or not they have signed into your site, as the plugins are served by Facebook.
Open Graph protocol
The Open Graph protocol allows developers to integrate your pages into the social graph. These web pages obtain the functionality of other graph objects including profile links and stream updates for connected users.
With the Facebook Credits API you can use credits as a method for buying digital and virtual goods within your application.