Headline tags start from H1 and go up to H6 in decreasing order of size. They play immense importance in your blog template optimization. Just as I earlier explained that a search engine robot reads your content just the way a human reads it. Headlines, bolded and highlighted texts draw attention. By default all blogger templates are designed such that the H1 tag is given to Homepage Main Title, H2 is given to Blog Description or Header dates, sidebar headers and H3 is assigned for post titles.