A spectrometer splits light into colors to show what materials are made of by measuring light's intensity and wavelength. It works by letting light enter through a slit, then using optics and a grating or prism to separate colors, which a detector measures and displays as a graph. They take light, separate it by wavelength and create a spectrum which shows the relative intensity of these separate wavelengths. The wavelength of light is then selected by the slit on the upper right corner. The core principle is simple: different wavelengths of light behave differently when they pass through a prism. A spectrometer is an analytical tool used across various scientific disciplines to measure how a substance interacts with light.