Drag is a resistive force that acts upon an object moving through a fluid, such as air or water. It always acts parallel to the direction of relative motion, opposing the object's movement and causing a reduction in kinetic energy. The magnitude of the drag force depends on several factors, including the fluid's density, the square of the object's velocity, and the object's geometry. Mathematically, the drag force is often characterized by an equation that incorporates the drag coefficient and the projected area of the object. Minimizing drag is a critical consideration in fields such as aerodynamics and hydrodynamics, as reducing this resistance allows for greater efficiency and range of motion.