GitHub

GitHub.com allows for cloning of existing repositories (such as the Office Dev PnP repos), or creating your own empty repositories.

You can then either edit projects and code copied from someone else's repository or commit your own code back to your own empty repository.

For efficiently working with GitHub, we recommend you to install the GitHub Desktop from https://desktop.github.com/. This small tool allows you to browse and modify the repositories easily with a rich desktop client.

As such, GitHub is typically the primary tool for open-source projects with needs for project management tools. There is also a commercial option for closed-source projects within GitHub.