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

Check out http://jcmc.indiana.edu/vol12/issue3/pan.html http://www.springerlink.com/content/l22811484243r261/

Some time spent on scholar.google.com might help you find what you are looking for