There's a whole lot of stuff that makes up a digital TV signal. Here's a primer on how it works.
In the beginning, there was analog television. You aimed the antenna, tuned in the channel, and then sat back to watch as the amplitude-modulated pictures flashed on the TV screen and the frequency-modulated audio blared forth from the speakers. Some time later, analog TV added color by shoehorning in a small signal with the necessary information amongst those amplitude- and frequency-modulated pictures and sounds.