Lift Theory explains how an object, like an airplane wing, generates lift to rise into the air. It is based on the principle that air moves faster over the top surface of the wing than the bottom, creating lower pressure above and higher pressure below. This pressure difference results in an upward force, allowing the aircraft to ascend. The theory is often illustrated using Bernoulli's Principle, which states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure. Understanding Lift Theory is essential for the design and operation of various flying vehicles, including helicopters and drones.