does armor rating on each of the pieces add up?

say you have 5 pieces (hood, robe, vambraces, leggings, shoes) of sunspear armor. how is your armor calculated? is 70 the total amount or is it 70x5=350 total armor?

No you don't get 350 armor rating. Wow that would be nice!

Your armor is what is stated on the armor pieces...all over. When you get attacked, an enemy only hits one of your armor pieces...so your example would be standard 70AL. Then you can upgrade it with insignias and the like to improve it slightly.

Also, there is a greater chance of enemy hitting you on chest pieces and leg pieces, so you might like to improve the armor rating on these pieces above the rest.

But yeah, it's 70 as a whole, not 350.

The armor is just 70. You have certain chances to hit a certain piec (higher % chance to hit the torso then you feet). And as the armor is base 60 , all damage is set on that (a 90 damage fire spell will do 90 damage on a 60 armor piece), and you have 10 more than that, thus will reduce the damage by something like 10% (every 40 more armor gives you half the damage).

Each piece is it's own armor. When you are hit it chooses a location.

So if you have a headpiece with 70 armor and +10 against fire for example and all the rest are just 70 armor.

You will have 70 armor against a fireball and if it hits your head armor you have 80 armor against that attack.

Does that help?

let's go through this again, please while i try to get it through my thick skull.

1st. how is the base armor 60 when for a dervish, for instance, it says it's 70?

2nd. a 90 damage fire spell does 90 damage on a 60 armor piece. so that is 30 more than that armor piece can take. does this mean that that 30 more is subtracted from your health points?

this is where i got completely lost:

Back in the day when I started playing I thought it added up. It impacted my gameplay for a few weeks because I thought skills like "Watch Yourself" were worthless (+20 armor when you have >180 armor?).

Ah the good old days of learning the game...

An example: let's say that fireball against 60 armor does 100 damage. Same fireball against 100 armor does 50 damage and 25 damage against 140 armor. So damage is halved every 40 armor. And the number 60 is when you take 100% damage from attacks and spells. Ofcourse armor ingore skills and attacks go through armor and do full damage always in normal conditions.

I suppose it would be best to provide the link to wiki about this rather than trying to explain it myself. Might just end up confusing you some more.

Here: http://wiki.guildwars.com/wiki/Armor_rating

1.
60 is just the base armor level for the purpose of damage calculation. 60AL means the skill used will do exactly the damage it states it will (at level 20 versus level 20). Don't even worry about this. All you should know is that different professions have different inherent armor levels.

2.
No. A 90 damage fire spell does 90 damage on a 60 armor piece. And that's the end of the story.

To clarify Smurf's point:
If you have +40AL you take half damage. For example, if a lightning spell hits a 60AL mesmer for 70, the same spell will hit a 100AL ranger for 35.

for your first point, they just meant 60 armor is the base for calculating domage.
for your second point, it seems like you're thinking about armor as having an absorbing property, lowering domage by a set amount for each hit you take.
armor actually has a multiplicative property, meaning certain armor levels correspond to certain multipliers. when you take domage (that isn't armor-ignoring) that domage is multiplied by whatever number corresponds with your armor. when you have 60 armor, that number is 1. when you have 100 armor, that number is .5.

that's awesome, cheers. i better start reading up.

now, i want to better myself and be the best player i can be. i'd love to be able to hold my own against the better players in pvp, and with time, i can hopefully be, but do all these numbers and arcane maths really help you in playing better and beying more competitive? do i need to start learning all the ins and outs of armor rating and all this crazy theorycrafting to be worth anything in pvp?