The six ability scores are Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma. These six scores are the fundamental measures of a character’s ability. Each class has certain prerequsite scores for some of these abilities.
The higher a score is, the better, and each score has positive and negative effects on certain aspects of the character. These effects are summarized on the tables below.
Generating Ability Scores
During character creation, each ability score is generated by rolling 4d6 and dropping the lowest die. The scores are then arranged as desired for the six abilities.
For main player characters, if the generated scores do not contain at least one score of 15 or greater, ALL six scores must be rerolled. This continues until the array of generated scores contains at least one score satisfying that requirement.
The reason to do this is that players are more willing to be invested long-term in a main character which has at least one high score. The above reroll rule does not apply to any other kind of character, including henchmen: in those cases, the scores you roll are the ones you get.
The parenthesized numbers in the column for bonus HP only apply if the character is one of the martial classes (Fighter, Paladin, Ranger, Assassin.)