Why does a plane move even when the wind is pushing against it?

The airplane's engines give it a certain speed through the air, called it's "airspeed". If the airplane's airspeed is greater than the windspeed, it will move forward over the ground. If it's airspeed is less than the windspeed, it will move backward over the ground. If it's airspeed is exactly equal to the windspeed, it will hover motionless over the ground.