Air resistance, also known as drag, is a force that opposes the motion of an object moving through the air. It occurs because air molecules collide with the surface of the object, creating friction. The amount of air resistance an object experiences depends on its speed, shape, and surface area. For example, a car moving quickly will face more air resistance than a bicycle moving slowly. Air resistance plays a significant role in various activities, such as skydiving and aerodynamics. In skydiving, a diver experiences increasing air resistance as they fall, which eventually balances the force of gravity, leading to a constant speed known as terminal velocity. Understanding air resistance is essential for designing efficient vehicles and improving performance in sports.