Here's why:

* Contact Forces: These forces occur when two objects physically touch. The force is exerted by one object directly on the other. Examples include friction, normal force, and applied force.

* Non-Contact Forces: These forces act on objects even when they are not touching. Examples include gravity, magnetic force, and electrostatic force.

Air resistance arises from the interaction of an object's surface with the air molecules it encounters. The object's movement pushes against the air molecules, creating a force that opposes its motion. This interaction is a direct physical contact, making air resistance a contact force.