Github is a service that allows you to store any form of source code in a repository in your account. While most people use the free service for open source projects, Github has paid accounts that lets you store source code in private repositories only accessible by authorized people. The git program can access any git repositories out there including on Github and with Xcode, you can push and pull source code on Github.For a single developer, you may not really need it, but with a private account you can store your project source code on Github, access it from anywhere and use it as an offsite backup. Like if you have a desktop machine and a laptop, you can push your code to Github from the desktop, then take your laptop with you somewhere and pull down the source and keep working on it.Github has other stuff too, like gists, which are one page repos for sharing snippets of code. For example, here's one I wrote that shows how to create an Automator action