Web Dev Academy Core languages · HTML Tool 1 / 64
Core languages

HTML

The skeleton of every web page. It defines structure and content — and modern HTML can validate, autocomplete, show popovers and more, all on its own.

Demo 01

Native form validation — zero JavaScript

Attributes like required, type="email", pattern and min make the browser validate the form for you. Submit it empty or with a bad email — the browser blocks it and explains why.

<input type="email" required>
<input type="text" pattern="\d{4}" required>
<input type="number" min="18" max="99">
Demo 02

Rich input types

HTML gives you specialised inputs that bring their own UI — date pickers, colour pickers, sliders. Try them; they're all native.

Demo 03

Autocomplete with <datalist>

Bind an <input> to a <datalist> and the browser offers suggestions as you type — no JavaScript.

Demo 04

Popovers & disclosure — interactive, no script

The popover attribute and <details> element give you toggles and modals with pure HTML.

Hi! 👋

This popover opened with popovertarget — a single HTML attribute, zero JavaScript.

What is semantic HTML?

Using the right element for the job — <nav>, <article>, <button> — so browsers, screen readers and search engines understand your page.

Why does structure matter?

Good structure means accessibility, SEO and styling all become easier. CSS and JS are layered on top of solid HTML.

Demo 05

Progress, meters & tables

Built-in elements for showing data — <progress>, <meter> and the humble <table>.

Upload progress:

Disk usage:

ElementPurpose
<header>Top of a page or section
<main>The primary content
<footer>Closing content
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Built with only HTML — every demo above uses native HTML elements and attributes (forms, input types, datalist, the popover attribute, details, progress/meter, table) with no JavaScript. The page's colours and spacing come from the shared CSS shell.

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