"AC" is your armor class. It is a number from -100 to 100, roughly defined as: armored like a tank -100 extremly shielded -90 heavily shielded -80 shielded -70 extremly heavily armored -60 extremly armored -50 very heavily armored -40 heavily armored -30 very good armored -20 good armored -10 completely armored 0 fully armored 10 armored 20 slightly armored 30 fully protected 40 protected 50 slightly protected 60 fully clothed 70 clothed 80 almost naked 90 naked 100 A piece of armor with AC 8 will set your armor from 100 to 92, for example. The lower your AC, the more will the damage of the enemies stroke be reduced. Sometimes items gives boni or mali to 'ARMOR'. A negative ARMOR improves your AC. for example, a sword giving -3 to Armor will decrease your AC from 100 to 97. Note: Items with AC (not armor) worn on head, legs and body protect more than other pieces of armor.