Flat Screen TV - Plasma Versus LCD Screens
There are two competing flat screen technologies that are dominant today: Plasma screens and LCDs. Both have 3" to 5" thick cases, and come in very large sizes. There are some differences in the technologies, however.
Plasma screens can be thought of as arrays of tiny (very tiny) neon bulbs that radiate in the traditional three colors TV (and computer images) are made up of - red, green and blue. These cells are all smaller than the smallest picture element (pixel) used to make up an image, and because they turn on and off at the rate that voltage runs through them, they are very responsive. Because they're self illuminating, a black image is one where the cell is turned off, so they have richer black levels.
LCD displays use a liquid crystal matrix; when a liquid crystal draws a current, it straightens out. As it straightens out, its optical properties change, much the same way that twisting a prism can make different colors. LCD displays have the advantage of being much lower power consumption devices than a plasma screen - they're more power efficient and "green" in terms of how much electricity they use. However, LCD pixels are not self illuminating, this means that there has to be a back light behind them to see the image at all; this means that even the darkest blacks have some light coming through them, which can be distracting when watching DVDs.
Older LCD screens used compact fluorescent backlights; modern screens use arrays of LED lights, lined up precisely with the screen. In addition to being lower consumption than even the compact fluorescents, these LEDs can also take up to 256 brightness levels from digital controls, which greatly reduce the "black level" problems.
Modern LCD screens have response times measured in 2 to 3 milliseconds or less for black to white transitions and 3 to 5 milliseconds for color transitions. This response rate is a vast improvement over the 20 millisecond response times of even five years ago, and has (mostly) gotten rid of the problem of "image smear" when playing high speed video games or watching sports.
Moving can also affect your choice of TV. As stated above, the plasma screen is composed of small neon lights, meaning gas. Laying the TV on the wrong side, or small bumps can cause the lights to break and the gas dispel. LCD TVs tend to be more durable and be set down by movers on any side and still work when your move is complete. So if you move a lot, say like in the military, LCD should really be your choice.
At this point, LCD screens are winning on performance, and on price, save for specialized applications - they're cheaper to make, they're available in more sizes, and most of the technical drawbacks to them have been ameliorated by clever engineering. Plasma displays are still the way to go for any application that needs a wide viewing angle (like in a bar), or needs to be VERY bright (for outdoor display.)