Redshift measurement is a fundamental aspect of observational astronomy that involves measuring the redshift of distant celestial objects, such as galaxies and quasars. Redshift is a measure of how much the light from an object has been stretched or shifted towards longer wavelengths due to the expansion of the universe. This phenomenon is a direct consequence of the Doppler effect, where sources moving away from an observer appear to have their light shifted to longer wavelengths. By measuring the redshift of an object, astronomers can determine its distance from Earth, as well as its velocity and the rate of expansion of the universe. Redshift measurement is a crucial tool for studying the large-scale structure of the universe, the evolution of galaxies, and the nature of dark energy.