Skill points represent how adept a character has been at learning skills, determined by class and intelligence. These are used to buy skill ranks, with ranks in those skills closely related to the character's class (the class being increased, in the case of multiclassed characters) costing fewer points than skills less closely related. In this way, class is a significant factor in both the type and quantity of skills a character can possess.
Each class has a number of skill points (from 2 to 8) it receives each level. To this is added the intelligence modifier, subject to a minimum of 1 skill point, and the sum is quadrupled at character level 1. These points are then available for immediate spending on ranks, or they may be saved and carried over to future level-ups. The costs and limits for skill ranks depend on the class being acquired, not the class that granted the skill points being spent, so it is not uncommon for players to "skill dump", saving skills from one class to be spent later with another class' costs and limits. (This is permitted by the game, even though the ability to save skill points was likely motivated by a much more limited use, specifically compensation for the inability to buy half ranks in a skill.)
If you buy a class skill, your character gets 1 skill rank (equal to a +1 bonus on checks with that skill) for each skill point. If you buy other classes' skills (cross-class skills), you get 1 rank per 2 skill points.
- Your maximum rank in a class skill is your character level + 3.
- Your maximum rank in a cross-class skill is one-half of this number (round down).
Using Skills: To make a skill check: 1d20 + skill modifier (Skill modifier = skill rank +ability modifier + miscellaneous modifiers). This roll works just like an Attack roll or a Saving throw, the higher the roll, the better. Either you're trying to match or exceed a certain difficulty class (DC), or you're trying to beat another character's check result.
Skill Ranks: A character's number of ranks in a skill is based on how many skill points a character has invested in a skill. Many skills can be used even if the character has no ranks in them; doing this is called making an untrained skill check.
Ability Modifier: The ability modifier used in a skill check is the modifier for the skill's key ability (the ability associated with the skill's use EG. Str, Dex and others). The key ability of each skill is noted in its description.