Level
Source Player Core pg. 11
A level is a number that measures something’s overall power. Player characters have a level, ranging from 1st to 20th, representing their level of experience. Monsters, NPCs, hazards, diseases, and poisons have levels ranging from –1 to 30 that measure the danger they pose. An item’s level, usually within the range of 0 to 20 but sometimes higher, indicates its power and suitability as treasure.