What does a red-shift mean?

A redshift refers to the phenomenon where light from an object, such as a galaxy, is shifted toward longer wavelengths, or the red end of the spectrum. This effect is primarily caused by the Doppler effect, where objects moving away from an observer appear to have their light stretched. In astronomy, redshift is often used to indicate that an object is receding from us, which supports the expansion of the universe. The greater the redshift, the faster the object is moving away, providing insights into the universe's age and the rate of its expansion.