GitHub is a web-based Git repository hosting service that offers all of the distributed revision control and source code management functionality of Git combined with a unique set of other features.In layman's terms, it's a place where every developer (or aspiring developer) can share their source code and stories with the world. It's a huge and highly respected collaboration platform, and it's used by just about every big technology company you can think of: Google, Twitter, Mozilla, Facebook, IBM, Netflix, Dropbox, and PayPal, to name a few. So, why did they all choose GitHub?