How does the Cosmic microwave background radiation support the Big Bang theory?

The cosmic microwave background radiation was first
detected by physicists in 1965. The radiation did not seem to be originating from any
particular location in the sky but was uniformly spread out. Using radiation from black
bodies, scientists were able to place the temperature that could result in the radiation
at 3.5 K

A search for the cause of this radiation revealed
that it is a remnant of the Big Bang that led to the creation of the universe. As the
universe expands, due to the Doppler effect all light that we observe is stretched and
there is a reduction in its frequency. The earliest light emitted when the Universe was
just created has been stretched out over billions of years to the frequency of
microwave. The uniform expansion of the Universe makes the microwave appear as cosmic
background radiation. The detection of this radiation provides further proof for the Big
Bang Theory, which postulates that the Universe originated from a single point, 15
billion years ago, in what can be called a giant explosion and is commonly referred to
as the "Big Bang."