Understanding Google Rich Snippet

Question

Reading about Rich Snippet SEO, I got to know that we need to markup our data to qualify for Rich snippet card. Looking into the source of Top10 website, I found out that it didnt had schema.org/og definition that would mark their site up. To backup my claim, I checked the same on Google Structure Data Testing Tool and, as expected, it returned nothing.I want to know how google is displaying the data on the Rich Snippet card. PS:- I read somewhere Google does not use their Knowledge Graph for Rich Snippet.