The Power of Meaningful Structure: Exploring Semantic Markup, Accessibility, and SEO

By Tony Vlachakis (SEO Strategist) and Manoli Vlachakis (Content Writer)
Last modified: June 5, 2024

This is an introduction to semantic markup and its impact on accessibility and SEO. Whether you're passionate about web development, coding, cybersecurity, or simply want to understand how web sites work, this information will prove valuable.

What is Semantic Markup?

Semantic markup uses meaningful HTML tags to convey two important things about web content; structure and meaning.

Instead of using generic tags like <div>, you use specific tags like <h1> for headings, <p> for paragraphs, and <table> for tables. This creates a clear and understandable structure for both humans and computers.

Think of semantic markup like adding labels to your web site content.

Instead of a plain box labeled "Content," you have specific labels like "Heading," "Paragraph," or "Image." This helps everyone understand the purpose and meaning of each element on the page.

Page Structure versus Visual Presentation​

The appropriate use of headings, paragraph text, and bullet formatting (by using unordered and ordered lists) ensures web content is structured correctly.​

Semantic markup conveys context and meaning, not just for presentation elements.​ Again, semantic markup allows web pages to be both human-readable and machine-readable.

Benefits of Semantic Markup

Semantic markup isn't just about aesthetics; it has real-world benefits. It allows everyone, regardless of their abilities, to access and understand your web site's content.

It also increases your web site's visibility in search engine results, potentially reaching a wider audience.

Finally, it makes your website easier for developers to work with, saving valuable resources and time. To summarize, here are the benefits of semantic markup:

  • Accessibility: Semantic markup helps assistive technologies like screen readers understand the content and present it appropriately for users with disabilities.
  • SEO (Search Engine Optimization): Search engines can better understand the content and context of your web site, leading to improved ranking in search results.
  • Maintainability: Semantic code is easier to understand and maintain for web content managers and developers, saving time and effort in the long run.

Accessibility and Semantic Markup

By using semantic markup, you're contributing to a more inclusive web experience.

Individuals with visual impairments or mobility limitations can navigate and understand your content effectively. This not only fulfills ethical obligations but also expands your potential audience. Here are some important accessibility technologies to be aware of:

  • Screen readers: Semantic markup allows screen readers to announce the type of content (e.g., heading, paragraph, list) and navigate the page efficiently.
  • Keyboard navigation: Users who rely on keyboards can easily jump between sections, forms, and buttons using semantic elements.
  • Alternative text (aka ALT TEXT): Images should have descriptive alt text associated with them, allowing screen readers to convey the meaning of the image.

Screen Readers​

Using semantic markup positively impacts the accessibility and visibility of your content.​

Some visitors use screen readers to navigate information on web pages utilizing the cascading headings as a table of contents.​

Without correct headings, some screen readers may have difficulty finding information on your page.​

Semantic markup adheres to accessibility guidelines according to section 508 compliance.

Screen Reader Demo for Digital Accessibility

Listen to Marc Sutton, from the University of California IT Web Services Department give a brief tour of screen reading technology.

Structuring Text​

Use headings and paragraph styles to format text on a page.​ Headings should be used in numerical and hierarchical order.​

Content Management Systems (CMS) or web design software, like Adobe Dreamweaver, have Heading 1 through Heading 6.

As a rule of thumb, Heading 1 should be used once per web page.

Major topics should acquire a Heading 2, while subordinate topics a Heading 3, 4, 5, or 6.

Importance of Using Accessible Headings

The following video demonstrates the proper implementation and use of headings. Mario Eiland from Portland Community College shows the comparison of inaccessible and accessible headings side by side using NVDA, a screen reader with Chrome browser.

SEO and Semantic Markup

Search engines, like Google, use the structure and content of your web pages to determine its relevance for search queries.

Semantic markup provides clear signals about the meaning of your content, making it easier for search engines to understand and index your web site. This can improve search rankings, potentially driving more organic traffic to your web pages. So using semantic markup also increases the likelihood users finding your page using search.​

When web pages DO NOT use semantic markup properly, search engines may not rank them at the top of the search engine result pages (SERPs).

Think of semantic markup as a way to communicate effectively with search engines. By using clear and descriptive tags, you're helping search engines understand what your web pages are about and who it's relevant to. This can significantly improve your web site's visibility and attract more visitors through search.

Semantic Markup - Best Practices​

  • Use headings (h2, h3, etc.) to structure content​
  • Do not alter style of a heading by making it bold, italic, increasing the size, etc.​
  • Do not make a heading a link​
  • Use bold and italics sparingly in paragraph text​
  • Never underline text for emphasis, use bold instead​
  • Underlining text is a visual queue on the web for a link and should not be used to indicate emphasis.​


Semantic markup is not just a technical detail; it has a significant impact on accessibility, SEO, and the overall user experience.

By adopting semantic markup practices, you can create web sites that are:

  • Accessible to a wider audience
  • Optimized for search engines
  • Easier to maintain and understand