The Raman effect is a phenomenon in which light interacts with molecules, resulting in a change in the light's wavelength. When a beam of light, usually from a laser, passes through a sample, most of the light is scattered elastically, but a small fraction is scattered inelastically. This inelastic scattering occurs due to energy transfer between the light and the molecules, leading to shifts in the light's frequency. This effect was discovered by Indian physicist C.V. Raman in 1928, earning him the Nobel Prize in Physics in 1930. The Raman effect is widely used in spectroscopy to identify molecular structures and analyze materials, making it a valuable tool in chemistry and biology.