Wave theory is a scientific concept that explains how waves propagate through different mediums, such as air, water, or solid materials. It describes the behavior of waves, including their speed, frequency, and wavelength. This theory is fundamental in understanding various phenomena, including sound, light, and ocean waves. In the context of light, wave theory suggests that light behaves as a wave, allowing it to exhibit properties like interference and diffraction. This theory was further developed by scientists like Thomas Young, who conducted experiments demonstrating the wave nature of light through the famous double-slit experiment.