Red shift is a phenomenon associated with what?

Redshift is a phenomenon associated with the increase in the wavelength of light from an object, indicating that it is moving away from the observer. This effect is commonly observed in astronomy, where it is used to measure the velocity of galaxies receding from Earth, providing evidence for the expansion of the universe. It can also occur due to gravitational effects, known as gravitational redshift, and in the context of the Doppler effect, where the relative motion of an object affects the frequency of the emitted light.