If you were to look closely at your television or computer screen, you would see that the picture is made up of thousands of tiny little dots. In fact, if you looked extremely close you would see the dots are really squares made up of three colors - red, green, and blue. Combined, these three colors can make up any color of the rainbow - up to 16.8 million colors to be exact. These dots are called pixels, and the more your screen has, the sharper the picture is. Your computer screen has a higher resolution than your TV screen, and that is why your computer's picture looks so much better.
Pixels are arranged in a grid on computer and TV screens. In fact, a screen's resolution is measured by the number of vertical pixel rows and horizontal pixel columns. Your current television can display up to 720 columns of pixels and 486 rows (349,920 total pixels). Your computer screen probably displays 800 columns of pixels by 600 rows (some computers display a higher resolution). A high definition television can display up to 1920 columns of pixels and 1080 rows (2,073,600 total pixels). In other words, the dots of color on a high definition television are much smaller and much closer together thereby resulting in a much more detailed and clear picture than you get on your analog TV today.