Semantic HTML is the bedrock of accessible web design. It's about using HTML elements for their intended purpose, providing meaning and structure to your content. This not only benefits search engines but, more importantly, assistive technologies used by people with disabilities.

For example, instead of using a <div> styled to look like a heading, use <h1> to <h6> for headings. Use <nav> for navigation sections, <article> for independent content pieces, and <aside> for related but separate information. This provides screen readers with the necessary context to understand the page structure.

Key benefits include improved screen reader navigation, better SEO, and easier maintenance. Start by reviewing your existing HTML and replacing generic <div> and <span> elements with more meaningful semantic tags.