What Does Facebook Graph API Mean?
A Facebook Graph API is a programming tool designed to support more access to conventions on the Facebook social media platform. The core of Facebook’s platform is something called the "social graph," which is the element responsible for facilitating all of the online relationships between people, places, things, etc. The Facebook Graph API specifically supports the extension or use of the graph by developers.
Google retired Social Graph API in April of 2012.
Techopedia Explains Facebook Graph API
A key part of the Facebook Graph API is a list of tags for different object attributes. By using these provided standards, developers can ensure that their changes match the conventional syntax commonly used for Facebook pages and objects. For example, the API can include a tag like name or user identifying a specific party, or numeric tags for Likes and other quantifiable activities, to keep track of how many of these functions have been applied to a given Facebook entity.
The Social Graph API is an automated way for Web pages to declare social connections between themselves. For example, many websites link out to their own Twitter page. Behind the scenes, the link is done in a way that allows developers of social products know that there’s a social connection between the two.