Non-Gamer's Guide to This Post
A damage meter is an addon that scans the combat log and adds up everyone's damage, healing, etc, so that you can look at the totals of your group.
Threat and its consequences is what makes Warcraft different from many other games. The person with the most threat is the one that enemies will attack. Certain classes, specifically warrior, are designed to produce more threat than any other class so as to keep the enemies on themselves and off of the rest of the group. This is called tanking. The main role of healers is to keep the tank alive. Any well-balanced party has a tank and healer. However, damage classes can sometimes have more threat than the tank by doing too much damage.
When the enemies are focused on you, you have aggro. Having aggro is the tank's most important (one might say only) duty.
I've been sick with a bad cold and therefore unable to attend regularly scheduled instance runs, one of which my husband ran with our family and an extra guy (taking my place) who kept trying to top the damage meter.
The problem with trying to out-dps everyone else is that you aren't playing smart -- you're too busy throwing spells around to manage threat properly. Therefore, this friend kept pulling aggro from the tank and forcing the healer to concentrate on him. Luckily, the group was mainly geared in Karazhan epics and it was a regular instance, so there were no wipes. Unluckily, this probably reinforced the friend's sense that it was okay not to manage his own threat.
My husband said later, "I read something that I think is true most of the time: 'If the tank dies, it's the healer's fault. If the healer dies, it's the tank's fault. If the DPS dies, it's his own fault.'"
Our paladin friend called it Big Number Syndrome, where a person is too enamored with their numbers to realize that they're playing badly -- forcing the healers to take care of them instead of the tank.
Something similar happened when our paladin friend pugged an instance as the tank -- a hunter kept forcing his pet to take aggro, then would laugh and say, "How is a hunter going to tank like a Pally!" The healer whispered: "Poorly." Then the hunter got upset that his pet kept dying, as the single healer couldn't keep up three tanks at once.
Not managing threat properly gets you killed, but it can also a) kill your party and b) maim your raid.
I, personally, am struggling with managing my threat. Not because I want to out-dps anyone, but because I completely ignore the numbers. They confuse me. Someone posts a damage meter in raid chat and all of a sudden my vision starts swimming and I want to take an aspirin.
I just want to be able to sit back and zap things until they die. Unfortunately, you can't always do that. Certain enemies don't respond to warrior maneuvers like taunt, which means that the tank wouldn't be able to save you if you took aggro. Last night in Karazhan, someone wondered if these special anti-taunt mobs were put in to teach people how to manage threat.
I think so. I think threat is the controlling factor of dps classes -- and the mark of a good player is knowing when it's okay to top the dps charts . . . and when it's not.
For me, I need to care a little more about numbers. I have Pretty Dress Syndrome, which is the opposite of Big Number Syndrome and probably just as dangerous.
Try downloading Omen Threat Meter (which is compatible with the other popular threat meter, KLH) and practice keeping an eye your threat. It's like checking your mirrors while driving -- unnatural at first, but you get used to it.