Sound is classified as a mechanical wave that requires a medium, such as air or metal, to propagate, unlike light, which can travel through a vacuum. Sound waves consist of the movement of atoms or molecules in the medium, which carry energy through compressional waves. While sound itself is not energy in the same way light is, it represents a transfer of kinetic energy through the medium. Light, on the other hand, is made up of photons, which are wave packets of energy that do not require a medium and consist of oscillating electric and magnetic fields. This distinction highlights the fundamental differences between sound and light waves in terms of their propagation and energy transmission mechanisms.