Your character has developed skills and knowledge as part of their career as an adventurer. Skills are things that most adventurers have learned to do, while knowledge is what they know. Skills might include the ability to perform athletic endeavors (swimming, climbing, running), the ability to sneak up on someone quietly, or even just the knack of persuading a humble shopkeep to give you a bit of a discount. In addition to those skills, you might also have specialized knowledge about certain adventuring topics like animals, magic items, or poisons. As your character advances, you gain both skill and knowledge points that you can allocate to represent the training and knowledge that is unique to your character.
Each level, your character gains skill ranks. The number of ranks you gain depends on your class. Investing a rank in a skill represents a measure of training in that skill. You can't have more ranks in a skill than your character level, though some abilities grant bonus ranks and boost this maximum.
| Progression Tier | Skill Pts Per Level | Classes |
| Low | 2 | Alchemist, Cleric, Fighter, Magus, Oracle, Paladin, Sorcerer, Warlock, Witch, Wizard |
| Medium | 4 | Barbarian, Druid, Inquisitor, Monk, Ranger |
| High | 6 | Rogue, Bard |
Like skills, your character gains knowledge ranks every level too based on your class. Just like skills, you can't have more ranks in a topic than your level.
| Progression Tier | Knowledge Pts Per Level | Classes |
| Low | 2 | Barbarian, Cleric, Fighter, Monk, Paladin, Sorcerer, Warlock, Witch |
| Medium | 4 | Bard, Druid, Inquisitor, Magus, Ranger, Rogue |
| High | 6 | Alchemist, Oracle, Wizard |
In addition to class-based ranks, you also get bonus ranks, which can be applied to either knowledge or skills. The number of bonus ranks you gain each level is equal to your Intelligence bonus. Humans gain 1 additional bonus rank each level on top of that.
Some skills are particular to certain characters' backgrounds (Locks, Performance, Tracking, Traps). These skills require a proficiency before they can be training or used. In most cases, certain classes being with the proper proficiency. Rogues, for instance, start knowing a bit about locks and traps. At the GM's discretion, sometimes characters who don't start out proficient in these skills can learn them as they advance.
Just because you know a skill doesn't mean you will be successful at it. In order to determine success, whenever you attempt to use a skill, you must make a skill check. When you make a skill check, you roll 1d20 and then add your score for that skill. Your skill score for each skill is
# of ranks + the appropriate ability modifier for the specific skill + any other bonuses
If the result of your skill check is equal to or greater than the difficulty class (or DC) of the task you are attempting to accomplish, you succeed. If it is less than the DC, you fail. Any roll that is more than ten (10) points less than the DC is considered a catastrophic failure. Catastrophic failures for some skills are more severe than a normal failure. Unlike attack rolls, saving throws, and regular ability checks, there are no critical successes for failures for skill checks. You fail or succeed by the merits of your skill alone. This means, there will be some DCs that you simply will never be able to do until you train further. Additionally, some skills with low DCs you will automatically always be able to perform.
Some skill checks aren't made against a set DC. Instead, they're opposed by a skill check from another player or NPC. In that case, your roll must exceed that of your target.
Sometimes, a task is simply not possible. If the GM determines that a certain thing you are attempting to do simply isn't realistic or possible, they should tell you so without necessarily requiring a skill check. Likewise, if a possible task has a DC that is too high for you to succeed at (20+Skill Modifier), they may also just say so without requiring a roll. However, sometimes for narrative reasons it's important for you to not know that the task is impossible. In this case, the GM may ask for a roll anyway, to make it seem feasible.
If a task is obviously easy for you (like opening an unlocked chest) the GM should also just tell you that you're successful without asking for a skill check. Some difficult tasks can also be considered automatically successful if there's no time pressure and no penalty for failure. In such cases, anything with a DC of 10 + your Skill Score is automatically successful without requiring a roll.
If a task is repeatable and there's no penalty for failure, you can choose to "take 20." This means that you are able to continually try a task until you are as successful as you can possible be at it. In this case, there's no need to repeatedly roll skill checks until you succeed. When taking 20, any task with a DC less than or equal to 20 + your Skill Score is automatically successful.
Some tasks take longer than others to perform. The GM will determine exactly how long a task takes. Some skills, like picking locks, finding traps, or picking a pocket, probably take about a standard action to perform in combat. Others, like climbing, swimming, hiding, or acrobatics, are movement-dependent and take place as part of your movement action. Other tasks may take several rounds or minutes, at the GM's discretion.
When taking 20 to automatically complete a task, the GM may tell you will be successful, but have you roll a skill check anyway to determine how long it takes to complete. If you hit the DC on a single roll, the task succeeds in one round. If not, the time it takes may be minutes or hours, depending on how close you get to the DC on your roll.
For most skills, each character will make a skill check for their own attempt at that task. Climbing ropes, picking locks, swimming across a river, balancing across a narrow ledge -- these are all things that each character must succeed or fail on their own. Some tasks, however, can be performed as a cooperative effort. In such cases, the person with the highest skill will simply make one skill check but at advantage.
Some tasks require the whole group's effort. For instance, if the entire party is attempting to ram a tree against a door to break it. The GM might require a certain number of members to lift the tree, and then each member will roll an athletics (or strength) check. For this type of task, all party members roll their checks and at least half need to hit the DC. Natural 20's count as two successes; natural 1's count as two failures.
In some cases, multiple players will make the same skill check separately. For instance, if an NPC is lying to the players, each player one after another might want to try to do a separate Insight check to judge the NPC's motives. In these cases, the GM may roll the checks as a group or as separate individuals. When rolling as a group, the GM may choose for players to make the check individual or as a group. When rolling individually, the GM should consider rolling each check for the players in private and giving the players separate responses. This way players would have to judge for themselves which response is accurate.
Knowledge checks are designed to help you adjudicate the depth of your character's knowledge about certain topics. They are made similarly to skill checks. The Skill Score is calculated in the same manner, and rolls are performed in the same way. As with skills, there are no critical hit or failures for knowledge checks, though on a catastrophic failure of a knowledge check, your character actually believes incorrect information about the subject at hand.
Unlike skills, which can always be attempted, if you don't have at least one rank in a topic, then you don't know enough about it to make a knowledge check.
Unlike some skills, knowledge checks are not repeatable. If you fail a knowledge check about a certain topic, you cannot re-attempt that check until you have added a rank to it.
Knowledge scores can be used to identify creatures and their abilities. The following knowledge topics are used to identify the following creature types.
If you succeed on a knowledge check against the creature's save DC, you identify it and learn one of the following about the creature: all of its resistances, all of its vulnerabilities, all of its bypasses, all of its immunities, its lowest or highest saving throw, all of its senses, or one of its special abilities. For every five points above the DC, you learn an extra fact about the creature. You may only make a knowledge check about a creature once unless you are a ranger (see the Ranger class).
As with skill checks, some knowledge checks are impossible to succeed; the topic is simply too obscure for you to reasonably know anything about. The GM should let you know this without requiring a check.
Unlike skill checks, there is very little room for auto-success when making knowledge checks. You either have some understanding of the topic in question or you don't. However, when it comes to mundane or common knowledge topics, you should carefully consider what you know about the world around you. If undead are common knowledge and not something out of folklore in your world, you may recognize them and guess the name of one that you see, even if you don't have points in religion. Likewise, you always have fluent knowledge of your primary languages and don't require linguistics checks for those. And you don' t need to know much about animals to own a pet--though you might, if you want to train it.
If you are attempting to discern how much your character knows about a topic, then the GM might simply rules that you can make a knowledge check without taking any extra actions. For topics that require figuring out how something works (like examining the engineering of a castle) or using that knowledge in a practical way (like making an animal check), the GM will determine how long the task takes. Finally, craft skills have a very specific amount of time required to complete them (see Crafting).
When determining how much you know about a subject, knowledge checks are never made as a group, nor can an ally assist. Each player must make a separate check to determine what they know about the subject. Practical knowledge (like training animals) can be done as a group though. And all crafting skills, including poison or magic item creation, have their own rules for collaborative creation (see Crafting).