What it is
Heading tags come in six levels, from <h1> (the main title) down to <h6> (the smallest subheading), and they're meant to be used in order to build a nested outline of a page's content — one H1 at the top, H2s for its main sections, H3s for subsections within those, and so on. "Heading hierarchy" simply refers to whether a page's headings actually follow this nested order, or whether levels get skipped or used out of sequence, like jumping straight from an H1 to an H3 with no H2 in between.
This is easy to get wrong when headings are chosen purely for how they look (picking whichever heading level happens to render at the desired font size) rather than for what they mean structurally.
Why it matters
A well-structured heading hierarchy functions like a table of contents built directly into the page — both search engines and screen reader users rely on it to understand how a page's content is organized and to jump directly to the section they care about. Skipped or disordered heading levels break that outline, making the page's structure genuinely harder to follow programmatically, even when it still reads fine visually to a sighted visitor scrolling normally.
Getting this right doesn't require adding more headings than a page needs — it simply means using the levels a page does have in the correct nested order, rather than skipping around based on font size alone.
How to fix it
- List out every heading on the page in order, noting its level (H1, H2, H3, etc.) — most browser accessibility tools or extensions can generate this outline automatically.
- Confirm the page has exactly one H1, followed by H2s for major sections.
- Check for any heading level being skipped — for example, an H2 followed directly by an H4 with no H3 — and adjust to fill in the missing level or lower the skipped heading.
- If a heading was chosen purely for its visual size rather than its structural place in the outline, change its heading level and adjust its font size separately with styling instead.
- Re-run your Launch Readiness check to confirm the hierarchy is now consistent.