Level 2 — Intermediate

These lessons cover form validation and advanced form features, complex tables, accessibility (accessible names, ARIA, landmarks), meta tags, SEO and structured data, responsive images, captions, iframes and embeds, details/dialog/popover, global and data attributes, connecting HTML to JavaScript and CSS, internationalization, and the document head. Recommended: the Level 1 lessons, especially document structure, semantic layout, and forms.