another really common 4:3 device is the iPad. Your HDTV is even wider. It has an aspect ratio of 16x9, or 1.78:1 (again, 1.7777...). So for every 16 inches wide your TV screen is, it's 9 inches tall.

Basically, there are two types of displays still in current use, the older 4x3 CRT displays, and the newer flat panel 16x9 displays. Within each display area, a range of images of varying aspect ...