Skills
The primary way a character will interact with the world is through Skills. Skills are calculated by taking the two stats specified and adding your Mastery in that skill. The Stats represent the character's raw talent while Mastery is practice and learning put into the Skill.
Example: Stat 1 + Stat 2 + Mastery = Skill Total.
Standard Skills
Standard Skills are Skills that have two set Stats to determine the character's talent in it. Some abilities and improvements may allow you to substitute one of the Stats with another.
Example: Melee Weapon Skill = STR + Dex + Melee Skill Mastery
Non-Standard Skills
Non-Standard Skills have on Stat that is set but the second can be chosen by what is most appropriate to the skill. This is most prevelenat in artisan Skills.
Example: Craft(Jewelry) would be Dex + Per + Mastery.
Knowledge Skills
Knowledge Skills are similar to Non-Standard Skills with the exception that the first Stat is always Wits.
Example: Knowledge(Society) would be Wits + Pres + Mastery.
Professional Skills
Proffesional Skills have both stats determined by what would be most appropriate. They differ from Non-Standard Skill by the lack of physical good Produced.
Example: Proffesion(Lawyer) would most likely be Wits + Pres + Mastery.
Magical Skills
Magical Skills are Skills that can only be granted by your Class. Each Class that has the ability to cast spells will have a section that specifies the type of magic it casts, what schools are available to it, and what stats are used for it.
Example: A Wizard uses Wits and Comp to cast Arcane Magic.