Aerodynamics

To put it simply put, aerodynamics is how things move in air. There are 4 main forces that act upon objects when it comes to aerodynamics.

WEIGHT - Everything on Earth has weight due to the force of gravity. To remain airborne, an aircraft needs something to push it in the opposite direction from gravity.

LIFT - This is the force that counteracts the force of gravity. To fly, the lift must be greater that that of the weight. An example would be an airplane in which its wings generates the lift it needs to fly. The amount of lift created greatly depends on the shape.

The shape of the airfoil allows for greater lift.

DRAG - Drag is a force that tries to slow something down. It makes an object harder to move due to the force pushing it back. The shape of an object also changes the amount of drag. The more air that hits a surface, the more drag it makes. 

THRUST - Thrust is the force that counteract the force of drag. Thrust is the push that moves something forward. For an aircraft to keep moving forward, it must have more thrust than drag.

When you add them together.