HTML has six heading levels — <h1> through <h6>. They are not just big bold text; they define the semantic document outline that search engines crawl, screen readers navigate, and browsers display. A well-structured heading hierarchy is one of the highest-impact things you can do for SEO and accessibility.
1-B 2-C 3-A 4-B | 5 6 6 h1 7 = h1 title, h2 sections, h3 subsections 8 = They are semantic - use CSS for sizing 9 = Ambiguous main topic - bad for SEO and accessibility | 10 = <h2>Features</h2>