Why do wings keep a plane in the air?

As the plane flies through the air, the upper surface of the wing, or aerofoil, is so curved that it creates higher air speed and lower pressure. In other Words this lower pressure gives an upwars"lift" to the aerofoil, wheras the air rushing under the aerofoil creates higher air pressure giving an upward "push" to the aerofoil. So both surfaces create upward forces.