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.
Miscellaneous Modifiers: Miscellaneous modifiers include racial bonuses, Armor check penalties, and bonuses provided by feats, among others.