GitHub is a web-based platform and repository for version management of source code of mostly Open Source software projects. Version control is based on Git, the software for distributed version control. In addition, GitHub allows efficient collaboration with third parties thanks to functions such as pull requests, access control, error tracking and task management.

Every change (commit) in a GitHub repository can be referenced via a unique URL. Using the existing Zenodo integration, a release can also be published or archived on Zenodo with the corresponding assignment of a DOI. To specify the desired citation, GitHub supports the Citation File Format (CFF), which was specially developed for software and code. The tool CFF Init can be used to create the required CITATION.cff file.

Tip: 

A tutorial by US scientists Richard W. Evans and Jason DeBacker offers a good introduction to the use of GitHub and Git.