Where can you play Dungeons dragons online?

"no" is an utterly ridiculous answer. Whoever put that should have done more research, as all you have to do is google "Dungeons and Dragons Online" and you will find a multitude of links to ddo.com. That stands for Dungeons Dragons Online, for those who see this and were wondering.

Updated 2/28/2011 (Duvik didn't write anything above this line)

I don't think the original question is referring to the MMORPG known as DDO. I think he is asking how to play traditional style dungeons and dragons online. The original Pen and Paper Roleplaying game that is now in its fourth iteration.

So, the best answer to that version of the question is...

Anyone can play pen and paper style Dungeons and Dragons online for free at The Tangled Web.

They use Virtual Game Tables like OpenRPG and Maptool in order to roll dice, display maps, display miniatures, chat, and create character sheets.