The armor rating is the total amount of armor a player has.
The effect of armorEdit
Armor rating helps prevent damage, the higher the armor rating, the less damage a player will take from incoming attacks. This scales for damage over time.
The effect of armor is non linear diminiuative return scale, though it may be linear on a staged system. This means that the higher your armor rating, the less extra effect an additional armor point has.
How to improveEdit
This can be improved by equipment, such as armor and shields.
The armor rating can be seen ingame when accessing the skill tree, then selecting the defense tab on the left. There the armor rating will be shown and when hovering over the armor rating, the amount of damage reduction against monsters of the player's level will be shown. Generally speaking, monsters of lower level will have their damage reduced more, while monsters of higher level will have their damage reduced less.
This can easily be seen once you level up. Just before leveling up, your armor rating will give you are percentage of damage reduction, while after levelling up, that same armor rating will give you slightly less damage reduction (about 1-2 percent).