Each character in Fallout is defined by seven attributes: Strength, Perception, Endurance, Charisma, Intelligence, Agility and Luck. Each attribute has a rank, from 4 to 10, or more. Whenever you try to attempt a skill test, your S.P.E.C.I.A.L. attributes form one part of your target number, when you roll your pool of d20s.

• Strength measures your character’s physical prowess. It is used to make melee attacks, increases melee damage, and influences how much stuff you can carry.
  
  
• Perception influences how easily you notice danger and how aware you are of your environment, affects your turn in the initiative order in combat, and is used to make attacks with energy weapons.
  
  
• Endurance describes your toughness and resilience, influences how many health points you have, how easy you find it to shrug off the physical dangers of the wasteland, and your ability to wield heavy weapons.
  
  
• Charisma influences how effectively you can convince people of your opinions, change their minds, barter with people, and find safety; among others.
  
  
• Intelligence measures your smarts, how you apply your mind to an obstacle, and how much you remember and know from studying the world around you.
  
  
• Agility measures how fit and agile you are, your balance, athletic suppleness, and how precisely you can control your body. It is used to make ranged attacks with small guns.
  
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  Luck describes just how much fortune smiles down on you, turning fickle forces in your favor, and generally coming out on top when you should be at the bottom. Luck gives you points to spend to add story details; use your Luck attribute when you make skill tests, and re-roll dice.