There is a word "sponsored" on top of some of the cards, so "native advertizing"
Yep, this is it. I charge sponsors on a CPC basis. In the near future I'll be doing actual interviews with sponsors, so readers will get to know all about how they started their companies, too.
Where / how did you reach out to these sponsors? I run a website in the travel industry and would like to add some advertising on it as well