Chapter 23: Perks.
Even within the same class, parties typically do not have the same training and skills related to combat. Perks is a mechanic that acknowledges this. Every party has at least three of them, which helps make them more unique compared to others. Some might be more athletic or more resistant to fire. These could tie into their backstory, such as being an athlete with the former or a firefighter with the latter (which is appropriate, because firefighters typically have ladders). This chapter explains the rules relating to perks.