Six abilities provide a quick description of every creature's physical and mental characteristics:

• Strength, measuring physical power
• Dexterity, measuring agility
• Constitution, measuring endurance
• Intelligence, measuring reasoning and memory
• Wisdom, measuring perception and insight
• Charisma, measuring force of personality

Is a character muscle-bound and insightful? Brilliant and charming? Nimble and hardy? Ability scores define these qualities — a creature's assets as well as weaknesses.

The three main rolls of the game — the ability check, the saving throw, and the attack roll — rely on the six ability scores. The book's introduction describes the basic rule behind these rolls: roll a d20, add an ability modifier derived from one of the six ability scores, and compare the total to a target number.