As ubiquitous as it is, GitHub is a little baffling for beginners because it's not evident at the start how it actually works. So, GitHub made a video to help make sense of it all.
The video is essentially a beginner's guide to GitHub's terminology, how it works, why you'd use it, and more. It walks you through how pull requests work, when you'd fork a project, and more. It's a straightforward introduction that doesn't provide much more than a few vocabulary words, but it's still useful for anyone new to GitHub.
What Is GitHub? [YouTube]