Stellar spectra are the patterns of light emitted or absorbed by stars, revealing important information about their composition, temperature, and motion. When light from a star passes through a prism or diffraction grating, it separates into different colors, creating a spectrum. Each element in a star's atmosphere absorbs specific wavelengths of light, resulting in dark lines known as absorption lines. By analyzing these absorption lines, astronomers can identify the elements present in a star, such as hydrogen, helium, and carbon. This process, known as spectroscopy, helps scientists understand the physical properties of stars and their evolutionary stages, contributing to our knowledge of the universe.