Semantic HTML refers to the use of HTML markup to reinforce the meaning (semantics) of the content within web pages, rather than merely to define its presentation or appearance. It involves using HTML elements that convey the purpose or role of the content they enclose, such as <article>, <section>, <nav>, <header>, <footer>, and <aside>, as introduced in HTML5. These elements provide a clearer structure to web documents, making content more accessible to assistive technologies, improving search engine optimization (SEO), and facilitating maintainability for developers.
Prior to HTML5, structural divisions were often created using generic elements like <div> and <span> with class or ID attributes, which offered no intrinsic semantic meaning. In contrast, semantic elements explicitly define parts of a document—for example, <nav> indicates a navigation section, and <article> represents a self-contained composition.
The use of semantic HTML supports web standards and promotes interoperability across devices and platforms. It plays a significant role in enhancing web accessibility, as screen readers and other assistive technologies can interpret and navigate content more effectively when appropriate semantic tags are used.
This approach is a core principle of modern web development, encouraged by the World Wide Web Consortium (W3C) and widely adopted in best practices for front-end development.