What causes Google search to display a byline for a GitHub repo?

Question

When I do a Google Search on certain GitHub repositories, I see a byline and a date on the third line (following the URL). For example, the "by D Stark - 2016" line in the following screenshot. What causes this information to be displayed and what is the root source of the information?

Answer 1

The author at the top is decorated with itemprop="author" which I believe trigger this schema http://schema.org/author.

Edit: if you copy-paste the HTML into https://search.google.com/structured-data/testing-tool you'll be able to see everything that is parsed. Marking HTML elements is one way to do it, another one is to build special json elements that contain this data. Ref https://developers.google.com/search/docs/guides/intro-structured-data