Obscure HTML
This page was taken from http://obscuretags.com

XMP

The XMP tag displays its contents without interpreting HTML inside it, so it prints <'s and >'s. On this page, the samples (in green) are displayed using XMP.

ISINDEX

ISINDEX creates an entire form, including the horizontal lines. Type stuff in the box and ENTER, then look at the URL

<isindex prompt="An isindex tag in the head generates this search form: " action="index.html">
Image in HTML source

Send an image as base64 text right in the src URL!

Definition lists: DL DT DD

A lot like the other lists... so much so that I betcha didn't even know they existed. It is pretty handy, though.

Stuff I like to drink
Soy milk
RC Cola
Coffee
Stuff I like to eat
Beef jerkey
Fruit rollups
<dl> <dt>Stuff I like to drink</dt> <dd>Soy milk</dd> <dd>RC Cola</dd> <dd>Coffee</dd> <dt>Stuff I like to eat</dt> <dd>Beef jerkey</dd> <dd>Fruit rollups</dd> </dl>
PRE takes arguments

They seem to fail in IE6.

COLS is the number of letters per line

Hello
from the abalone ballroom.
<PRE WRAP COLS=6> Hello from the abalone ballroom. </PRE>
DEL INS STRIKE

According to the President, we should stay the course we've never been stay the course.

Strike just prints like this

<p> According to the President, <del datetime="20060830" cite="http://www.whitehouse.gov/news/releases/2006/08/20060830-10.html">we should stay the course</del> <ins datetime="20061021" cite="http://www.washingtonpost.com/wp-dyn/content/article/2006/10/23/AR2006102301053.html" >we've never been stay the course</ins>. </p> <p>Strike just <strike>prints like this</strike></p>
BDO

The BDO tag is pretty cool! The BDO tag is pretty cool!

It seems to be for sticking bits of Hebrew or Arabic into leftarian pages.

<p>The BDO tag is pretty cool! <BDO dir='rtl'>The BDO tag is pretty cool!</BDO></p>
ACRONYM ABBR

ACRONYM gives hover definitions (ABBR fails in IE6)

I had to LOL!!! at the ABBR tag. I had to <acronym title='Laugh out Loud'>LOL!!!</acronym> at the <abbr title='Abbreviation'>ABBR</abbr> tag.
OPTGROUP

OPTGROUP puts section names in a SELECT list:

Who is your favorite rapper?

<select> <optgroup label="N.W.A."> <option value ="cube">Ice Cube</option> <option value ="dre">Dr. Dre</option> <option value ="ren">MC Ren</option> <option value ="easy">Easy E.</option> </optgroup> <optgroup label="Wu-Tang Clan"> <option value ="rza">RZA</option> <option value ="gza">GZA</option> <option value ="ghostface">Ghostface Killa</option> <option value ="odb">Old Dirty Bastard</option> </optgroup> </select>
LABEL extends a radio box hit area

LABEL extends a radio box to include the label to it.

You'll see the effect if you click on the words "yes" or "no" below.

Is this a totally retarded idea?

<p> <form name="labelExample" action="isindex.html"> <kbd>Is this a totally retarded idea?</kbd><br/> <input type="radio" name="retarded" id="retardedYes" /> <label for="retardedYes">Yes</label> <input type="radio" name="retarded" id="retardedNo" /> <label for="retardedNo">No </label> </form> </p>
BUTTON

Except for anchors and other buttons, most anything can be put on a button.

<button style="background-color: #aabbff;" onclick="alert('You pushed the button!')"> <b> <font color="#ff0000">Button</font>. <font size="+2" color="#008800">tag</font> <font color="#0099ff">action</font>. <br/>With linebreaks! </b><br/> <table border='1'> <tr><th colspan='3'>And a table!</th></tr> <tr><td>1</td><td>2</td><td>3</td></tr> <tr><td>4</td><td bgcolor='#ffee00'>5</td><td>6</td></tr> <tr><td>7</td><td>8</td><td>9</td></tr> </table> </button>