The Graph API is the primary way that data is retrieved from or posted to Facebook. It is a low-level HTTP-based API that you can use to query data, post new stories, and a variety of other actions that an app might want to do. We will be using this API heavily to get the Facebook data into the client application. These API requests are composed using the browser's built-in Ajax capabilities and also some third-party node modules like request JS. You can get more details about the Facebook Graph API at https://developers.facebook.com/docs/graph-api/reference/user/friends/.