Accessibility rule: Headings are not structured, explained

Summary

Headings should follow a clear hierarchical structure (without skipping levels) to reflect the organization of the page. Properly structured headings help all users—especially those using assistive technologies—understand, navigate, and trust the content layout.

Overview

Organizing web pages by headings helps users get a sense of the page’s organization and structure. Properly nested headings present both visual and programmatic levels of importance. This check inspects if heading levels are used hierarchically so that no heading levels are skipped throughout the page.

Here is an example of a correctly nested heading structure:

• H1:Siteimprove solutions
  • H2: Accessibility & Digital Governance
    • H3:Quality Assurance
      • H4: Broken links
      • H4: Readability
    • H3: SEO Audit
    • H3: Policy
    • H3:Accessibility
      • H4: Confirmed issues
      • H4: Potential issues 
      • H4: PDF issues
  • H2: Content Experience
  • H2: Marketing Performance

Who is impacted by this?

When page content is organized using headings, all users are able to skim through the content easily and get a sense of how the content is structured. Screen readers and assistive technologies rely on heading tags (<h1> - <h6>) to identify headings. If the heading skips a level, the user might wonder if they are missing some important content or context. If the text is only enlarged, bolded, or emphasized, but the correct heading tag is not used, screen readers will not interpret it as a heading. WebAIM screen reader user survey 9, concluded that almost 87% of respondents find heading useful.
Note: This rule is not required for conformance to any accessibility requirements, but it is a best practice.

How does this work?

The rule checks that every element, that has the role of a heading, is nested hierarchically. 

Related Content

You can read more about the SIA-R53 rule in Alfa, Siteimprove’s open source accessibility conformance testing engine.