Simply put, digital is the future of television. Even with the advent of color four decades ago, television has been broadcast in essentially the same way since it was invented before World War II. Television is now and has always been analog. But that format has all kinds of limitations, especially in the size and quality of the picture you see at home. Digital TV will eliminate those limitations. Digital television pictures are crystal clear, much sharper than anything you've ever seen on TV before. The sound quality is incredibly sharp too. Some programs will be broadcast in Dolby Surround Sound. You'll never want to go back to analog television. Digital is so much better that all existing television stations are required by the government to change over to the new format in the next few years. Analog TV stations will no longer exist.
Besides the difference in picture quality, there's a difference in picture size. Analog TV screens are 4:3...meaning they're four units wide for every three units high, almost square. Digital TV's are 16:9... meaning they're almost twice as wide as they are tall. That's the same size ratio as a movie screen, meaning you can see a lot more on each screen.