What evidence is there supporting the Big Bang theory?

In short, the universe is increasing. All of the galaxies we have observed that are great distance away are moving away from us. And the farther away they are, the faster they are moving away. It took small imagination to "rewind" that picture and see a time when all of the matter and energy of the universe was basically "in one place" and there was no universe. With all the energy (matter could not have exist as we know it in an energy field so intense) in that single place after arriving or being formed, a huge explosion, the Big Bang, formed space-time.