DOI (Digital Object Identifiers) are a very important and widely used tool to uniquely identify objects in academic literature and beyond - for instance, journal articles, research reports, but also code and data sets.
If you are a researcher who writes code and deals with primary data, you may want to archive your code and make it citable by assigning a DOI to your GitHub repository.
Follow this guide and learn how to do it using GitHub and Zenodo.