Redshift and blueshift are terms used in astronomy to describe how light from objects in space changes as they move. When an object, like a galaxy, moves away from us, the light waves stretch, making them appear redder. This phenomenon is known as redshift and indicates that the universe is expanding. Conversely, when an object moves toward us, the light waves compress, causing them to appear bluer. This is called blueshift. Both redshift and blueshift help astronomers understand the motion of celestial bodies and the overall dynamics of the universe.