What it measures

This metric checks whether your HTML heading structure follows a clean hierarchy — a single H1 tag, followed by H2 sections, with H3 subsections nested properly, without skips or duplicates.

Why it matters for AI

AI crawlers use heading hierarchy to understand your content's outline and determine what each section covers. When GPTBot or ClaudeBot reads your page, it builds a mental model of the content structure from headings. Skipping levels (H1→H3) or having duplicate headings confuses this model and reduces citation confidence.

Issue	Impact	Example
No H1 tag	Severe	AI can't determine the page's main topic
Multiple H1 tags	Moderate	AI sees competing "main topics"
Hierarchy skip	Moderate	H1→H3 (missing H2) breaks the outline
Duplicate headings	Minor	Repeated headings create ambiguity

How to improve

1. Use exactly one H1 tag — This should be your page's main title
2. Follow H1→H2→H3 order — Never skip from H1 directly to H3
3. Make each heading unique — Duplicate headings confuse AI parsers
4. Use headings for structure, not styling — Don't use H3 for visual size; use CSS instead