HyperText Markup Language (HTML)
The standard markup language used to structure and describe content and semantics on web pages.
HTML determines how content is structured for browsers, assistive technology and search engines, so its quality affects accessibility, crawlability, page performance and how easily a site can be maintained.
A content team replaces a page built from styled div elements with semantic HTML: one h1, nested h2 and h3 headings, nav, main and article landmarks, and descriptive alt text on 12 product images, then retests with a screen reader.
HTML defines structure and meaning, not visual design or behavior, which depend on CSS and JavaScript. Browsers tolerate invalid markup, so errors can go unnoticed while still breaking accessibility or structured data parsing.
An HTML document is a tree of elements written as tags with attributes, starting from a doctype and an html root containing head and body. Browsers parse the markup into the Document Object Model, which CSS styles and JavaScript can modify. The language is maintained as a living standard by WHATWG, and semantic elements such as header, nav, main, article, button and form give content meaning that assistive technologies rely on.
Experience Design, Search Optimization
WHATWG — HTML Standard: Introduction — https://html.spec.whatwg.org/multipage/introduction.html; MDN Web Docs — HTML: HyperText Markup Language — https://developer.mozilla.org/en-US/docs/Web/HTML