How does armor/armor piercing work?

[Wingflier]

Sorry, I've been curious about this lately and wanted to know.  I checked the wiki but the information there on the subject of armor and armor piercing is obscure at best.

I'm assuming that the armor value of a ship is a flat reduction of the damage done by another ship, but I could be wrong.

If armor value is a flat reduction of damage, does that mean armor piercing ignores armor to do that specific amount of damage anyway?  Also, is armor piercing affected by multipliers?  For example, if a ship has 750 armor piercing and a x4 multiplier against light hulls, does that mean it has 3,000 armor piercing against light hulls?

Sorry for the question, I just couldn't find the information I was looking for.

[Hearteater]

Check out this page on the wiki, specifically the section Armor Rating.  For your convenience:

Armor Rating
Armor does not affect the ability of one ship to hit another ship. Rather, it linearly reduces the amount of incoming damage, but not below a floor of 20% of the total amount of damage that would have been dealt. This makes highly-armored ships take longer to kill, but it doesn't make them any harder to hit. Armor is simply subtracted from the incoming damage (so 5000 damage against 1000 armor does a 4000 loss in hit points) down to a minimum to 20% of the base value (5000 damage against 5000 armor does a 1000 loss in hit points). Damage multipliers increase the base damage before armor is applied.

[Wingflier]

Okay, thanks for that, but now how does armor piercing work?

[Orelius]

Armor piercing makes an attack do damage according to the amount of armor minus the armor piercing.

Namely, if an attack does 5000 damage with 1000 armor piercing against a 4000 armor target, it'll do damage as if it were 5000 damage against a 3000 armor target, making it do 2000 damage.

Armor piercing, however, can not reduce armor below 0, so if you have 999,999 armor piercing against 100,000 armor, you'll just do damage as if the armor were 0.

[x4000]

Yep, exactly what Orelius said!