Hitrating, and why it is so important

Every day I log in I see this question flash a few times across the screen in /g "What stats should I focus on for [spec] for [class]?"

Well, the answer is 90% of the time the same: get hit capped first. And then most people realize they are not hit capped. Why is this important? I'll give a very brief example here, and keep it as short and simple as possible in order to prevent a lot of confusion:

We'll take a raid boss that is being DPS'ed by a frost mage as our example. Now, mages have a (without talents) 17% chance to miss a raid boss. Let's set a few ground 'rules' for this 'simulation' to work:

The boss fight lasts 6 minutes, or 360 seconds
The mage never has to move
The mage only casts Frostbolt
Frostbolt is a 2 second cast and hits for 10,000
A crit does 150% damage

Scenario 1: No stat adjustments

360 seconds divided by 2 seconds = 180 Frostbolts
180 Frostbolts - 17% (due to misses) = 149.4 Frostbolts (We'll round that UP in favor of not having hit rating (I actually am making the numbers look better then they would be) to 150 Frostbolts)
150 Frostbolts of 10,000 damage = 1,500,000

Total damage over 6 minutes: 1,500,000

Scenario 2: 10% crit chance

Still the same old 180 frostbolts of which only 150 will hit.
10% of 150 = 15 Frostbolts that crit
135 Frostbolts that do not crit = 1,350,000
15 Frostbolts that do crit = (15 * 10,000) * 150% (crit damage) = 225,000

Total damage over 6 minutes: 1,575,000

Scenario 3: 10% hit chance

180 Frostbolts - a 7% chance to miss = 167.4 Frostbolts that hit. (Again rounding up to stay consistent, that makes 168 Frostbolts)
168 Frostbolts * 10,000 damage = 1,680,000

Total damage over 6 minutes: 1,680,000

This is of course an overly simplistic calculation, but it should quickly demonstrate that hitting your target is important. I have not even touched on a situation whith procs, rotations, etc. Long story short: cap for hit.

You can see your chance to hit in your character screen in game, simply press 'C'. If the pane on the right hand side is not showing, click the little arrow in the bottom right hand corner and it will expand your character screen to include your stats. Hover over the 'Hit rating' and a popup will tell you the chane to hit a target at level 85, 86, 87 and 88/skull. The latter one needs to be 0% if you want to do more DPS on a raid boss.

The chance to miss there will vary on your class, spec and gear. It is safe to say that you should reforge all stats to get to 0%. Do not go over because that will be a waste of hit rating.

(While I am very aware of the fact that in certain circumstances hit rating capping is not as important as other stats, you should be aware (if you're intelligent enough to do the math and understand it) that whoever reads this for a resource is not at our level of comprehension yet. In order to not overwhelm that person and let them learn on their own, I ask you to refrain from correcting me here with far too indepth models of simulations.)