Character stats and derived stats:

The character stats are the fundamental properties of each character. His physical attributes, so to say. They divide into Strength, Perception, Endurance, Charisma, Intelligence, Agility, Luck and Courage (also called SPECIAL-C, due to the starting letters). From these values one derives the so
called derived stats and the starting values of the skills.

You get 45 freely distributable points to distribute on the character stats with human characters. But no stat may lie above or below the race maximum or minimum.

Now to the individual stats:

STRENGTH (ST): Pure, primitive bodily strength. Strength influences, among other things, how far your character can throw things, how well they do in close combat, how much damage they do unarmed, how much they can carry and how well they use bigger and really big guns.
Strength is therefore the most important stat.

PERCEPTION (PE): The sensual acuity of your character. Among other things, perception influences their medical skills, their skill in thieving and picking locks, their survival ability out in the wasteland and their use of technical gadgets of all kinds.
Perception is therefore the most important stat.

ENDURANCE (EN): The toughness of your character. Influences, among other things, their resistance to poison and radiation, their initial hit points, the rate of new hit points when reaching a new experience level and the ability to live of the land.
Endurance is therefore the most important stat.

CHARISMA (CH): A combination of looks and charm. Influences among other things, how people around you react on your character, their ability to influence humans (and similar) and to conduct trade.
Charisma is therefore the most important stat.

INTELLIGENCE (IN): Smarts and cleverness. Influences among other things, the medical knowledge of your character, their ability to live of the land or to use a computer or non electronic machines and the amount of skill points they gain with every new experience level.
Intelligence is therefore the most important stat.

AGILITY (AG): Agility contains the whole motor activity of your character. Influences, among other things, the skills sneaking, lock picking, pick pocketing, the ability to to live of the land, the ability to use non-electronic gadgets and also the amount of available action points in combat.
Agility is therefore the most important stat.

LUCK (LU): Luck is the strangest of all stats. Apart from your character's skill with games and gambles, it basically only influences one other derived stat: his (or her) chance to score a critical hit in combat. But it gets tested a lot for other things as well, and therefore influences everything a little
bit.
Luck is therefore the most important stat.

COURAGE (CO): Courage is the stat that indicates how easy it is for your character to endanger his (or her) body. Courage is therefore used for the skills tactics, driving (engines), riding, climbing, acrobatics and body control and also decides if your character will take a big risk.
Courage is therefore the most important stat.