What device is primarily used to control the lateral movement of an aircraft?

The ailerons are the primary control surfaces used to manage the lateral movement of an aircraft, allowing it to roll around its longitudinal axis. When a pilot moves the control yoke or stick left or right, one aileron will deflect upwards and the other will deflect downwards. This creates a difference in lift between the two wings, causing the aircraft to roll in the desired direction.

While other devices like the rudder also play a role in lateral control, particularly during coordinated turns, its primary function is to control yaw, or the side-to-side movement of the aircraft's nose. Elevators are responsible for controlling pitch and flaps assist in increasing lift and drag during takeoff and landing but do not directly manage lateral movement. Thus, ailerons are specifically designed for and are the most effective at controlling an aircraft's lateral response.