Pathfinder 2e uses a system of “traits” on nearly every noun in the game. Actions, ancestries, feats, items, spells, they all have traits. These traits both describe and categories the various rules entities.
Some traits don’t have an affect on their own, but might interact with other features in the game. For example, a feat might grant a damage bonus to all spells with the “fire” trait.
Some tags have specific mechanical effects. For example: The “uncommon” and “rare” traits indicate the rarity of an item (more on rarity later in these articles), while spells might have traits like “fire” or “polymorph”.