HTML

The template element and slots as the HTML foundation for Web Components.

Control how the browser fetches resources with resource hints and script loading attributes.

Add images with img, write useful alt text, and set width and height to prevent layout shift.

Structure pages with semantic elements instead of generic divs, and how they map to landmarks.

Build tables with table, tr, th and td, add headers, and know when a table is the wrong tool.

Build a working form, connect labels to inputs, and understand action, method and name.

Email, number, date, url and other input types, plus required, min, max and pattern for browser validation.

Choose between AVIF, WebP, JPEG, PNG and SVG, and control loading with loading, decoding and fetchpriority.

Embed audio and video with native controls, multiple sources, and captions with the track element.

What HTML is, how browsers turn it into a page, and how it works with CSS and JavaScript.

Make larger tables understandable with caption, thead, tbody, scope, colspan and rowspan.

Create an HTML file in a code editor, open it in a browser, and use DevTools to inspect it.

Every common form control, grouping with fieldset and legend, and default values.

How elements, opening and closing tags, void elements and attributes work, with the nesting rules that prevent bugs.

Help browsers fill in forms and show the right mobile keyboard with autocomplete, inputmode and enterkeyhint.

The skeleton every HTML page needs, what each part does, and the lang attribute.

Build disclosures and modal dialogs with no JavaScript framework, and their built-in accessibility.

What belongs in the head: title, character set, viewport, description, and links to CSS and icons.

Show menus, tooltips and pickers with the popover attribute and popovertarget, without JavaScript.

Use h1 to h6 to outline content and paragraphs for text, and why heading levels matter for readers and search engines.