Heading tags, <h1> through <h6>, define the structural hierarchy of a page's content for both readers scanning the page and search engines trying to understand what it's about. <h1> is the top-level heading, usually matching or closely echoing the page's main topic; <h2> through <h6> nest below it in decreasing order of importance, the way a document outline nests sections and subsections.
A page should carry exactly one <h1>, since it's meant to represent the single main topic of the page, while lower heading levels can repeat as many times as the content's actual structure calls for. Google reads heading text as a strong topical signal, close behind the title tag itself, which is why the <h1> in particular is worth writing to genuinely reflect the page's target keyword and topic rather than a generic label. Beyond SEO, well-structured headings are also a real accessibility requirement: screen reader users frequently navigate a page heading by heading rather than reading top to bottom, so a broken or illogical heading hierarchy, skipping from <h2> straight to <h5>, using headings purely for visual styling, makes a page measurably harder to use for exactly the visitors relying on that structure most.
