Bonuses and Penalties

Bonuses

If you have different types of bonuses that would apply to the same roll, you'll add them all. But if you have multiple bonuses of the same type, you can use only the highest bonus on a given roll—they aren't cumulative.

Proficiency bonus

Circumstance bonuses

Involve the situation you find yourself in when attempting a check.

Item bonuses

Are granted by some item that you are wearing or using, either mundane or magical.

Status bonuses

Typically come from spells, other magical effects, or something applying a helpful, often temporary, condition to you.

Penalties

Penalties work very much like bonuses. You can have circumstance penalties , status penalties , and sometimes even item penalties. Like bonuses of the same type, you take only the worst all of various penalties of a given type.

Source Pathfinder Player Core pg. 400