Definition. HTML that reflects the meaning of its elements: <article>, <section>, <nav>, <header>, correctly nested headings, native lists, <figure>/<figcaption>, plus suitable ARIA roles where needed. Non-semantic markup, by contrast, relies solely on <div> and <span>.

Why it matters. Semantic markup is the basis for accessibility, classic search and AI retrieval at the same time. It costs nothing extra to build, but it decides whether a screen reader, a crawler and an LLM see the same page structure.

Related. Retrieval-ready content, Structured Content, Entity-based SEO