What is XHTML and How is it Different from HTML?

What is XHTML?

XHTML (Extensible HyperText Markup Language) is HTML reformulated to follow strict XML rules. It was popular in the 2000s for enforcing clean, well-formed markup.

Key Differences from HTML

Rule	HTML	XHTML
Close all tags	Optional	Required
Lowercase tags	Optional	Required
Quote attributes	Optional	Required
Self-closing	<br>	<br />

Example

<!-- HTML (loose) -->
<P>Hello<BR>World

<!-- XHTML (strict) -->
<p>Hello<br />World</p>

Is XHTML Still Used?

Largely replaced by HTML5, which is more forgiving and feature-rich. XHTML's discipline influenced modern best practices though.

FAQs

Should I learn XHTML today?

Learn HTML5 instead. Understand XHTML's strict rules as good habits. More in our XHTML guides.

Why did XHTML decline?

Its strictness broke pages on minor errors; HTML5 won by being practical.