How does Google use HTML tags to enhance the search engine?

Question

I know that Google’s search algorithm is mainly based on pagerank. However, it also does analysis and uses the structure of the document H1, H2,

Answer 1

Like cletus said follow the google guidelines.

I did a few tests came to the conclusion that title, image alt and h tags the most important. Also worth to mention is google adsense. I had the feeling if you implement these, the rank of your site increase.