A diffraction grating is an optical device that disperses light into its component colors or wavelengths. It consists of a surface with many closely spaced lines or grooves, which can be made from materials like glass or plastic. When light hits the grating, it bends or diffracts, creating a spectrum of colors similar to a rainbow. This phenomenon occurs because different wavelengths of light are bent by different amounts. Diffraction gratings are widely used in various applications, including spectroscopy, where they help analyze the composition of materials by examining the light they emit or absorb.