It's easy to get confused between Git and GitHub, but there is a simple difference. Git is an open source tool, while GitHub is a web service that can function as a remote host for Git repositories. There is no strict dependency between the two, and you don't have to use GitHub or any other remote service (there are some others, such as BitBucket and GitLab) at all. Having said that, GitHub is a great way to store your code, collaborate on projects, and learn best practices. And not only that; to a large extent, GitHub is a social network for developers, and, on some occasions (say, while searching for a job), you might be judged based on the existence of an account and the quality of the code exposed on the service. 

GitHub serves as the remote server for your code. In the cloud, you can push your code there, and pull a new version back, manage branches, and so on. Due to its remoteness, GitHub can serve any machine; for example, you can develop the code on your local machine, and deploy the code from GitHub to your production servers. Furthermore, there is a large ecosystem of tools and services built around GitHub. Some of these will be covered in Chapter 15, Packaging and Testing with Poetry and PyTest.