Why does gravitational redshift occur and what is its significance in the field of physics?

Gravitational redshift occurs when light waves lose energy as they move away from a massive object, such as a planet or star, due to the gravitational pull. This causes the light waves to shift towards the red end of the spectrum. In the field of physics, gravitational redshift is significant because it provides evidence for the effects of gravity on light and helps scientists understand the behavior of light in strong gravitational fields, as predicted by Einstein's theory of general relativity.