Online Help

There are several areas that contribute to your Armour Class, or AC, and each
plays a part in determining your overall defensive score. These areas are
listed here, and briefly explained:
 
1. Dexterity Modifier
   -Your dexterity will greatly affect whether you are quick enough, or nimble enough
     to get out of the way of incoming blows. Keep in mind, your dexterity modifier is
     limited by the armour you wear, and the load that your character bears.
2. Size
   -Your size will obviously have an effect on your overall AC. The smaller you are,
    the better chance you have of avoiding harm, while the larger you are the opposite
    applies.
3. Armour
   -As you would expect, the heavier the armour that you wear about your character, the
    more protected your character will be from harm, however all of that extra weight
    will hinder your ability to dodge as well.
4. Shield
   -A shield can be used to keep a medium between yourself and your opponent, whether
    physical or through some magical means.
5. Natural Armour
   -Some races are born with very thick skin, some are born with thin, frail flesh. There
    is little one can do to improve this situation, though there may be a few magical means
    for those of a more adventurous nature.
6. Deflection
   -This area refers to the more mystic ways of protecting oneself. Some refer to it as
    magical protection.
 
* The last four of these are called "armour class bonus types." If you
have multiple objects that contribute to the same armour class bonus type, the
effects are not cumulative, they do not "stack."  So, for example, if you wield
two shields, you will only gain the shield bonus from one, that with the larger
larger of the two deflection bonuses will apply, and the other object will do
nothing (at least in terms of increasing your armour class deflection bonus.)