# Heading structure

_Source: https://seomatrix.ai/tools/structure/_

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## What it does

A heading structure checker validates that a page's headings form one logical outline: a single H1 that names the page, then H2s and H3s that nest without skipping a level (never jumping H2 straight to H4). A broken outline hides your document's structure from search crawlers and AI answer engines, which walk the heading tree to learn what each section answers — so a clean hierarchy makes your content easier to index, feature in snippets, and quote in AI Overviews.

## What it checks

- **Single H1** — The page has exactly one top-level heading that names the whole page; zero or multiple H1s blur the primary-topic signal crawlers rely on.
- **No skipped levels** — You never jump from H2 to H4 — each step down moves exactly one level, keeping the outline parseable by machines and screen readers.
- **Logical nesting** — Every H3 sits under an H2 and every H4 under an H3, forming a tree that mirrors the content's actual structure.
- **Empty headings** — An empty heading tag (no text) creates a phantom node in the outline and should be removed or given text.
- **Top-to-bottom order** — Headings appear in document order that matches the visible reading order. Returning to a higher level to start a new section (H3 back to H2) is fine — only skipping levels on the way down (H2 to H4) breaks the outline.
- **HTML and markdown parity** — The same rules apply whether you paste rendered HTML (`<h2>`) or markdown (`##`), because both resolve to the same heading tree.

## How to use it

1. Paste your HTML or markdown into the checker, or enter a URL to fetch the live page.
2. Review the flagged issues — a missing or duplicate H1, and any skipped level such as H2 jumping to H4.
3. Fix the outline so there is one H1 and each heading steps down a single level at a time, then re-check.

## FAQ

### Why should a page have only one H1?

The H1 tells crawlers and AI engines the page's main topic in one line, so a single H1 keeps that signal unambiguous. Multiple H1s split the primary-topic signal and can flatten your outline, while zero H1 leaves the page with no titled root.

### Does skipping from H2 to H4 hurt SEO?

Yes — a skipped level breaks the logical outline that crawlers, screen readers, and AI answer engines use to map sections to subtopics. It rarely triggers a penalty on its own, but it weakens content parsing and accessibility, which both feed ranking and citation.

### What is the correct heading order?

Start with one H1, then use H2 for main sections and H3 for subpoints within them, never skipping a level on the way down. You can jump back up (H3 to H2 for a new section), but each step deeper should move only one level at a time.

### Can I check markdown as well as HTML?

Yes — paste markdown (`#`, `##`, `###`) or HTML (`<h1>`–`<h6>`), or fetch a live URL, and the checker maps all three to the same heading tree. The hierarchy rules are identical regardless of the source format.