You're in my spot, Sir.

A crowd system is a way to handle a large number of characters at the same time in the same environment. They need to be able to move around and avoid each other. The agent tell the crowds system where it wish to go and it will get back a path and movement orders so it avoids running into other agents. For that the crowd system need access to the pathfinder search graph so it can see what parts are valid and can replan when paths collide.