The cosmic microwave background (CMB) is a form of electromagnetic radiation that is believed to be a remnant of the Big Bang. It is a faint background radiation that is uniform across the entire sky and is believed to be the oldest light in the universe. The CMB provides strong evidence for the Big Bang theory because its temperature is consistent with the predictions of the Big Bang model. Additionally, the CMB is believed to be the result of the expansion of the universe, which is another prediction of the Big Bang theory.
