XHTML is a stricter and cleaner version of HTML.
In this tutorial you will learn the difference between
HTML and XHTML. We will also show you how W3Schools.com was converted into XHTML.
Start learning XHTML
Test your XHTML skills at W3Schools!
Start the XHTML Quiz!
At W3Schools you will find complete references about tags, standard attributes, standard events, colornames, entities, character-sets, URL encoding, language codes, HTTP messages, and more.
XHTML 1.0 Reference