Methods used to map out a path of travel from one point to another, typically avoiding obstacles in the way.
This is a specific subset of ai which deals with how an entity determines the proper route from point A to point B.
In its simplest essence, it is the ability of an NPC to realize that there is a door next to them, rather than just ram head-first into the wall when trying to reach the next room. Complexity is introduced by factoring in the different kinds of obstacles, and what factors (time, safety, impressiveness) that the entity uses to pick from multiple applicable paths.