Header tags organize your page into a scannable hierarchy that Google's algorithms parse to extract meaning and topical relationships. The H1 declares your main topic, while H2–H6 tags break content into logical sections that map to user intent and search queries. When you use headers correctly, crawlers spend less time guessing what your page covers and more time indexing the nuances that differentiate you from competitors. Headers directly influence three ranking factors. First, they provide semantic context—Google's natural language models weight header text more heavily than body paragraphs when determining topic relevance. Second, structured content increases dwell time because users navigate faster to the section they need, sending positive engagement signals. Third, well-formed headers make you eligible for featured snippets and passage ranking, where Google pulls a single H2 section to answer a query even if your overall page ranks fifth. Common mistakes kill these benefits. Using multiple H1 tags dilutes your primary topic signal. Skipping heading levels (H2 to H4) confuses the document outline. Stuffing headers with exact-match keywords reads unnaturally and triggers over-optimization filters. Generic headers like "Introduction" or "More Information" waste semantic opportunities—describe what the section actually covers. At Ottawa SEO, we audit header structure in every technical review because it's low-effort, high-impact. A typical fix involves consolidating duplicate H1s, rewriting vague H2s to include question-based phrases that mirror People Also Ask queries, and ensuring mobile breakpoints don't hide headers behind accordions that block crawlers. We see 12–18% increases in impressions within four weeks when we restructure a flat-text page into a proper header hierarchy, especially on informational content competing for position zero. One tactical point: headers aren't just for SEO. Accessibility screen readers use them for navigation, and users on mobile skim headers before committing to a scroll. If your headers don't make sense when read in sequence without the body text, rewrite them. Good headers serve algorithms and humans equally.