Below is a list of some of the HTML 4.01/XHTML 1.0-compliant tags. There are many more, but some still aren't supported in even the newest browsers.

Tag	Source	Output
<bdo dir="rtl"> Defines text direction (rtl = right to left)	<bdo dir="rtl">Watch me write Hebrew</bdo>	Watch me write Hebrew
<br /> Inserts a line break	This text contains<br />a line break	This text contains a line break
<button> Defines a form button. Inside you can put formatted text or images.	<button>click me for <b>nothing</b></button>	click me for nothing
<del> Strikes through text	This text should be <del>deleted</del>	This text should be deleted
<ins> Inserts (underlines) text	This text should be <del>deleted</del> and this <ins>inserted</ins>	This text should be deleted and this inserted
<div> Used to format large blocks of HTML	<div style="background-color: #292929; color: white; width: 160px; height: 160px">This is a div</div>	This is a div with some style commands. Divs are cool!
<hr /> Inserts a horizontal rule	Some text<hr style="color: #666666" />Some text	Some text Some text
<img /> Defines an image	<img src="java.gif" alt="" />