From QWiki

Armor is a powerup that can be collected by walking over it, and which respawns 20 seconds after pickup. For the important armor on a map, such as RA, it can be strategic to pick it up every 20 seconds, thereby denying it to the opponent.

There are three types of Armor:

Armor types & absorption
Armor type Item armor green.png Item armor yellow.png Item armor red.png
Damage Absorption 30% 60% 80%
Armor amount 100 150 200

The type and value are important in the damage calculation (see below). Also your ability to pickup a "lower" armor is calculated by that. If your current armortype multiplied with your current armorvalue is bigger than those of the armor in front of you, you cannot pick it up. Example:

You picked up a Red Armor (type=0.8) earlier but the value is down to 120 (value=120) already. If you now come across a Yellow Armor (type=0.5, value=150). Now your type*value (0.8*120) equals 96. The Yellow Armor's is 75 (0.5*150). 96 is bigger than 75, so you cannot pick it up. But as you will see below, this is a good thing.

Combined Damage Points

Armor can be thought of as a component of the combined damage system, the other component being health points. A common illustration is the following DM6 scenario:

You have Red Armor and 100 health, e.g. 200/100, or a total of 300 combined health points.

Your enemy has MH and GA, e.g. 100/200, or the same total of 300 combined health points.

At this moment in time, it is totally correct to say that you and your opponent are 100% evenly matched (all other things being the same). (Of course, very soon the megahealth will begin to count down, and you will no longer be 100% evenly matched, also the megahealth has go down to 0 to respawn, while the RA doesnt have to go down at all, it only has to go down as little as 1 point to be picked up, so there is a lot less time of risk for the person who controls RA)

Absorption of Damage

However, different armors absorb damage differently, and the above scenario can be used to further illustrate this concept. Suppose you and your enemy still have 300 combined health points, you with RA 200/100, him with MH/GA 100/200. Now:

You hit 2 direct rockets (for 200 points) and your enemy hits you with 2 direct rockets (also for 200 points). Lets forget that direct rockets are sometimes more than 100 points each. So, each of you now has 300 minus 200 points, but now you are no longer 100% evenly matched (even if the MH does not count down). Why not? Because RA absorbs a lot more damage than GA. After some math, here are the two components after one direct hit:

You have RA40/60

Enemy has 0/100

Trivially, you can now gain an edge simply picking up some health boxes, while your opponent needs another armor to regain the edge over you. As a side effect, you should now also know that the MH will spawn in 20 seconds, pick up your armor in 10 seconds, pick up the MH in 10 more, and now you will be able to lock that MH, because as long as you have it -- it will not spawn.

Absorption rates:

  • GA: 3/10 of damage goes to armor
  • YA: 3/5
  • RA: 4/5

QuakeWorld terminology
Game stuff
Quad | Ring/Eyes | Pent
GA | YA | RA | Mega
Axe | SG/Boomstick | SSG | NG | SNG | GL | RL | LG/Shaft
Binds | Bunnyhop | CFG | Demo | Duel | FFA | Frag | Rocket Jump | GLRJ | rpickup | pickup
Cam | Flood | +forward | BG | CS | GG | HPW | LPB | MGT | MST | Kenya | Rapecloset | TB3 | Stomp | BO3 | BO5 | Div1 delay | kpickup