Ranks: Ranks represent how much raw training or practice you have put into a skill. A character receives a fixed number of ranks per level equal to 4 + Int. Modifier. Additional ranks are granted based on your background, Race, and Class.
The maximum ranks you can put into a skill equals {Level + Relevant Ability Modifier}; if it is a trained skill, then the maximum number of ranks you can place in the skill equals {1+ Level + Relevant Ability Modifier}. At first level, this maximum is {1 + Relevant Ability Modifier} or {2 + Relevant Ability Modifier} if it is a trained skill. If the relevant ability modifier is a penalty, then it cannot reduce the maximum number of ranks you can put in a skill below 2. Of course, as you level up, your maximum number of ranks in any particular skill also increases, up to a fixed maximum of 10 ranks, or 12 ranks for trained skills.
Trained Skills: Trained skills are a limited list of skills that you have specifically devoted extra time to learning. A list of trained skills is given under your class, while additional trained skills are granted by backgrounds. You may choose a number of skills from the list and add an extra rank to them at first level. Should backgrounds or classes give you the same skill, then you can get an additional rank up.
Difficulty Class (DC): A number that tells you how easy or how hard a skill check is.
Why are you even rolling?: DC <5
So Simple, a Caveman could do it: DC 5
Easy: DC 10
Average: DC 15
Challenging: DC 20
Hard: DC 25
You probably shouldn’t be doing this: DC 30
Your Screwed: DC 35
Inconceivable: DC 40 (absolute maximum)
Skill Check: When attempting to use a skill you roll 1d20 + (Total Relevant Skill). If it equals or exceeds the DC set by the GM, then you succeed in using the skill successfully. If not, then you fail.
Passive Checks : Basically, when your not threatened, you can use your passive skill to determine success. A passive skill check is equal to 10 + (Total Relevant Skill).
Opposed checks : Sometimes you aren’t facing against a specific difficulty, but rather pitting your skills against another person. In that case, the GM determines the skills used, and whoever has the highest roll succeeds. (Example Bluff vs. Insight). Sometimes the GM may elect to have the NPC or opponent use a passive skill instead, or you use a passive skill while the opponent rolls. This happens all the time in combat.
Advantage/Disadvantage: As determined by by character conditions, or the GM, players/NPCs could have advantage or disadvantage on a skill check or attack roll. When this happens, the player rolls an additional D20, taking the higher of the two rolls when at an advantage, or the lower of the two when at a disadvantage. In the case of more than one Advantage or Disadvantage for a single player, Advantages and Disadvantages cancel out. Whichever one is left over is what you apply. Only 2d20’s can be rolled.
Equipment: Various pieces of equipment can add bonuses or penalties to various skills. Enchanted weapons, for example may add bonuses to attacks and damage, when using them.
