The Facebook Platform is a standards-based web service with methods for accessing and contributing Facebook data. We've made the methods as easy to understand as possible, and included full documentation to help you learn more.
Facebook Developers Wiki
A deep resource for anyone developing on the Facebook Platform.
Interface (API)
The Facebook API uses a REST-based interface. This means that our Facebook method calls are made over the internet by sending HTTP GET or POST requests to our REST server. With the API, you can add social context to your application by utilizing profile, friend, photo, and event data.
Query (FQL)
Facebook Query Language, or FQL, allows you to use a SQL-style interface to more easily query the same data that you can access through other Facebook API methods.
Markup (FBML)
Facebook Markup enables you to build full Facebook Platform applications that deeply integrate into a user's Facebook experience. You can hook into several Facebook integration points, including the Profile, Profile Actions, Canvas, News Feed and Mini-Feed.
Add Developer Application
This is required to build a Facebook application as it allows you to manage your application settings, your API keys, etc.
Resources Section
Learn more about Facebook Platform with code samples, client libraries, and more.
Anatomy of a Facebook Application
An overview of the many integration points of a Facebook Application.
Tools
Prototype your Facebook Platform application in real-time with easy-to-use test consoles.