Each character will have a score ranging from 3 to 18 in each of the following abilities below (strength, intelligence, wisdom, dexterity, constitution and charisma). A bonus or penalty is associated with each score, as shown on the table. Each class has a Prime Requisite ability score, which must be at least 9 in order for the character to become a member of that class. There are also required minimum and maximum scores for each character race other than Humans (as described under Character Races).
As the name implies, strength measures the character's raw physical power and is the prime requisite for fighters (and the associated ability bonus or penalty is applied to all attack and damage rolls in hand to hand combat). Note that a penalty here will not reduce damage from a successful attack below one point.
This is the ability to learn and apply knowledge and is the prime requisite for magic-users.
A combination of intuition, willpower and common sense, wisdom is the prime requisite for clerics. The wisdom bonus or penalty may apply to some saving throws vs. magical attacks, particularly those affecting the target's will.
This ability measures the character's quickness and balance as well as aptitude with tools, and hence is the prime requisite for thieves. The dexterity bonus or penalty is applied to all attack rolls with missile (ranged) weapons, to the character's armor class and to the character's initiative roll during combat.
A combination of general health and vitality. The constitution bonus or penalty is applied to each hit die (level) rolled by a character (but a penalty will never reduce hit die rolls below one point).
This is the ability to influence people, as those with high charisma are well-liked and respected. Certain shopowners will also sell their wares at a less expense to those with high charisma.