S.P.E.C.I.A.L.
All character's have a maximum (although they may distribute less if they prefer) of 40 SPECIAL points to divide up as they wish. SPECIAL stats form the core backbone of what the character is physically and mentally. While their experiences and personality fill out their blank slate, so to speak, it is their SPECIAL statistics that determine the shape of that slate.
Strength
Strength (S) is a measure of a character's raw physical power. If you have high strength, you were probably a dominant personality during childhood. If you have low strength, you were probably pushed around by the kids with high strength.
Perception
Perception (P) is your character's general awareness and senses. In essence, Perception is your character's connection to the outside world. Touch, taste, vision, hearing, and smell are all controlled by perception. High perception characters will be alert and aware of the world around them, reacting swiftly and effectively. Low perception characters live in their own little world, and the worst of them seem to be totally oblivious of the world around them.
Endurance
Endurance (E) is a measure of your character's physical and mental grit. It is a direct measure of your character's general vitality and constitution. High endurance means a tough, healthy character who is rarely ill and does not tire easily, for whom everything is a flesh wound unless it hit bone and they can usually exert themselves for a long time. Low endurance characters will be the soft types, often sickly or easily hurt. These ones will tire more easily and will whine about their cuts and bruises.
Charisma
Charisma © controls the basic likability of your character, from your character's charm to their attractiveness. That twinkle in the eye and the sparkling ping in their smile. High charisma makes for a charming character who is easy to talk to and who can more easily influence people. Conversely, a low charisma character will be blunt, abrupt, aloof and untouchable - having trouble finding leadership positions, good deals, and friends.
Intelligence
Intelligence (I) is your character's brainpower. High intelligence characters will be competent, mentally skilled and rational, and often will often be knowledgeable about a number of subjects. Low intelligence puts a character on the opposite end of the scale. The worst will struggle to form words, much less full sentences and know little about fighting other than "The pointy end goes in the other guy". Best steer clear of them if they have explosives.
Agility
Agility (A) is a character's speed, agility (duh) and dexterity. High agility characters are swift and dexterous, able to react quicker than clumsier characters, able to strike several times before a foe can make return attacks. High Agility will also often produce a naturally more stealthy and flexible character. A low agility character, conversely, will be clumsy and relatively slow in their actions and reactions.
Luck
Luck (L) governs everything and nothing. It is a measure of how well life, fate, karma, god or whatever higher power your character believes in treats them. In general, it's safe to say luck plays some part in everything a character may do. A lucky character will find themselves in favorable positions, with random instances often working together to help you. The opposite, of course, happens to an unlucky character, who will be the one constantly finding gravelly patches of ground to sneak through or cow shit to slip in.