The Primary Flight Controls

Primary flight controls are the essential control surfaces of an aircraft. They contribute to the movement and control of the main axis's. 

The three primary flight controls are: elevator, aileron, rudder (EAR for short)

If you want further explaination and even details about the secondary flight controls, you can read this article by Embry-Riddle.

Elevator

The elevator controls the pitch altitude and therefore the planes' lateral axis. The elevator is located at the back and simultaneously goes up or down to control the pitch. 

Aileron

The Aileron controls the roll and the longitudinal axis of the air plane. In an elevator, both control surfaces move up and down simultaneously to control the pitch, but for ailerons, the control surfaces will be opposite.

Rudder

The rudder controls the yaw and the vertical axis of the air plane. The rudder moves left and right to control the direction the nose is pointing to.