The latest version is:
The Graph API is the primary way for apps to read and write to the Facebook social graph. All of our SDKs and products interact with the Graph API in some way, and our other APIs are extensions of the Graph API, so understanding how the Graph API works is crucial.
If you are unfamiliar with the Graph API, we recommend that you start with these documents:
Learn how the Graph API is structured, what access tokens are, and how versions work.
Explore the Graph API using the Graph API Explorer tool and run your first request.
Learn how to build complex queries, handle errors, debug, and more.
Learn how to read our reference documents so you can easily find what you're looking for.
We strongly recommend you start with the Graph API Overview to learn the structure of the Facebook Social Graph.