HTML5 is the markup language of the modern web. Every page, app, and email lives in some form of HTML. The good news: the core is small. Master a handful of structural ideas and you can describe almost anything.
1. Semantic Elements
Use tags that describe what the content is, not how it looks. Screen readers, search engines, and future-you will thank you.
<header>
<nav>...</nav>
</header>
<main>
<article>
<h1>Article title</h1>
<section>...</section>
</article>
<aside>Related links</aside>
</main>
<footer>...</footer>2. Forms & Inputs
HTML5 added many input types and validation attributes. Use them — the browser does the heavy lifting.
<form>
<label>
Email
<input type="email" required>
</label>
<label>
Password
<input type="password" minlength="8" required>
</label>
<button type="submit">Sign in</button>
</form>3. Accessibility (a11y)
- Always include
alttext on images. - Use one
<h1>per page; nest headings logically. - Label every form input. Implicit labels work too: wrap the input in
<label>. - Buttons are buttons. Don't use
<div onclick>.
4. Useful APIs to Know
- localStorage / sessionStorage — quick client-side persistence.
- Fetch API — modern way to talk to servers.
- IntersectionObserver — lazy-load images, infinite scroll.
- Geolocation, Clipboard, Notifications — opt-in browser powers.
Summary
Write HTML that says what it means. Keep it semantic, keep it accessible, and let CSS handle how it looks. Solid HTML is the foundation everything else stands on.