Why is a special cable required to view HD programs?

Question

When you purchase an HD television you have to purchase a separate cable to view HD programs. What is so special about the cable?

Answer 1

The cable is called an HDMI cable which stand for High Definition Media Interface, it enables the high def signal and digital audio to go through 1 cable. HD has a higher resolution than regular standard def thus requiring a cable that can handle that higher resolution giving you a superb crystal clear picture.  

Answer 2

you can still connect component cables (green,blue.red)and receive a decent picture.

Answer 3

This cable is specially designed to connect the HD receiver to the output equipment.  Without it, regular to bad picture.  With it, HiDef.  The reason for the special cable is to differentiate between other receivers and an actual HD receiver.  This is why HD is a bit more expensive.  That cable connects you to the HD equipment and it's the only way to connect you.  Does that make sense?