A plasma screen contains literally millions of gas-filled cells trapped between two pieces of glass. An electrical grid zaps these cells and causes the gases to ionize. The ionized gases, in turn, cause a layer of phosphor on the viewer’s side layer of glass to light up. Despite their compact dimensions, you can find plasma HDTVs in 42-, 50-, and even 60-plus-inch sizes. Imagine a 4- or 5-inch-deep HDTV that spans 5 feet diagonally, and you can see the instant appeal of plasma. Plasma HDTVs don’t rely on a light bulb shining through or reflecting off of something. Plasma brightness is even better than CRT’s in some ways because the picture is evenly bright across the entire screen. In a CRT, on the other hand, you always have some slight difference in brightness as the electron beam reaches different parts of the screen. The finest plasma TVs have such high resolutions that they look like nothing more than beautiful film images. All the pixels on the screen light up simultaneously. You can have progressive HDTV sources and non-HDTV sources displayed to full advantage on a plasma HDTV. Plasma displays have a good picture even when you’re sitting “off axis”. This is a huge benefit for smaller rooms, where viewers may sit relatively far off to the sides of the screen, at wider angles.