The same applies in smaller dungeons, tanks are expected to lead the pack, to take control. Of course, there are exceptions to this, it's a generalization which is not true 100% of the time. But I don't think it's unreasonable.
All this makes it a little harder to get started in tanking. So, WoW Insider has put together some tips for the novice tank.
Pulling is the term given to getting a group of mobs to hit you, instead of that mage over there. For most early dungeons, and several of the later ones too for that matter, the pull is half the battle. As long as you can get those baddies latched on to you, you're doing alright.
So how do you do it? Well, that is, of course, highly dependent on your class, but there are a few kinds of pull that I can run you through here.