Defense
A character or monster's defense rating is an aggregate of any bonuses from armor, their dexterity attribute, and any feats or Force powers that are active. Every character in the game has a base defense of 10, to which the aforementioned factors are added to form that character's overall defense. See the attack listing above to get a brief example of how defense works in combat.
Note that the defense score of your characters does not reduce the damage they take; it merely makes them more difficult to hit. Should an enemy's attack roll exceed your defense, the damage calculation takes place without regard to your defense score.
Non-Player Character (NPC)
NPCs are characters that are controlled by the computer. Since KOTOR only allows you to control one party member at a time, your teammates are, technically speaking, often considered to be NPCs, but for the purposes of this guide, we've attempted to reserve the "NPC" term for characters that are never under your control, such as townsfolk, combat opponents, and merchants. Your teammates will usually be referred to as, well, teammates, or party members.
Player Character (PC)
This term is used to refer to the character that you created at the beginning of the game; the character that is always in your party and is the focal point for the story that unfolds in KOTOR.
Saving Throw
A saving throw is what represents your character's ability to escape harm, or, failing that, minimize it through defensive actions. Every threat that forces your character to make a saving throw will have its own unique difficulty check.
There are three different kinds of saving throws: throws for will correspond to a character's ability to resist mental intrusion and mind-affecting attacks; throws for fortitude represent a character's natural resistance to poison and physical harm; and throws for reflex test a character's ability to avoid the brunt of explosive damage by diving out of the way.
For instance, assume a thermal detonator is thrown into a room where two of your characters are standing. Some damage from the explosion is inevitable for both characters, but one of them has a much higher dexterity than the other, giving them an advantage when it comes to quickly moving out of range of the explosion. The DC check of a thermal detonator is 15 against a character's reflex save. The less dexterous member of your party rolls a 10, which is unmodified by Dexterity, meaning that that character will take the full 60 points of damage from the Detonator. The other character rolls a 10 as well, but adds his Reflex bonus to the save, which just happens to be +5, meaning that he quickly finds cover before the explosion and only takes half damage.
Tank
When we say "tank", we don't literally mean that you get to play around with an M-1 Abrams or anything like that, of course. The term refers to the process of using a beefed-up character with high defense and/or vitality to engage your enemies in point-blank combat, while your weaker characters sit behind the lines and take potshots at your foes. Zaalbar performs this function admirably in the first sections of the game; Juhani or your PC will assume the role afterwards.