Rich snipped: non-google review-stars in SERPS

Hi there, I wonder if you can give me a hint. I am trying to understand how non-google review stars can appear within the SERPs. Example: Searching for the German business coaching provider “Intem” using the search phrase “intem verkaufstraining” - google displays a 4.5 star rating made up of 1.1.52 reviews. The point is: these reviews aren’t google reviews. They are gathered via a training feedback process that has been approved and verified by a quality certification institute (Zertifizierung von Qualitätsmanagementsystemen (ZQS)).

My question is: what does it take to build up a similar process, so that google approves these kind of reviews for displaying them in the SERPS.

I hope I made myself clear enough. In advance thanks a lot for your help.

Best, Holger

Website link:

Here is my site Read-Only: LINK
(how to share your site Read-Only link)

Hi, the star rating reviews in serp are generated via schema code, which you need to add to your website. you can visit the to know about the various types of schemas. If you need you can read the whole schema markup tutorial. what is schema?

Hi, thanks a lot for your hint. So far so clear. I checked via google richt snipped test on google search. And extracted the part:

name Verkaufstraining INtem
type: aggregateRating
ratingValue: 4.5
bestRating: 5
worstRating: 1
ratingCount: 1152

I only have one question: is there a valid source behind this or can just anyone put a rating value, count and gets the stars displayed in the SERPs for his page?

Thanks again so much for your support. Best Holger