The sexiest thing going in TV is flat panels--plasma and LCD screens that are only a few inches thick. But if you're not planning to hang your TV on the wall, is a flat panel the best way to go? And which are better: plasma or LCD flat-screen TVs? Here's what you need to know before you buy.

The Big Picture
LCD and plasma screens may look similar, but the underlying technologies are quite different, as are, consequently, their strengths and weaknesses.

The Specs Explained

Gone are the days when you figured out how big a screen you wanted, looked at some sets, and bought the one with the best picture that fit your budget. An options explosion has littered the shopping landscape with numbers, features, and terminology that even experts sometimes have trouble tracking. So we've tried to boil the choices down to the basics that can actually do you some good, and we've noted which are important. (In audio and video, never forget that just because something has a number to describe it doesn't mean it really matters!)

We've grouped the specs into three categories: important, somewhat important, and minor.
Important: Contrast Ratio

Contrast ratio refers to the brightest and darkest light values a display can produce at the same time. All else being equal, the higher the contrast ratio is, the better. All else is seldom equal, however. Pumping up the maximum light output, for example, can increase contrast, but it won't do anything to overcome poor black level, which tends to be a greater problem with plasmas and, especially, LCDs. So take contrast ratings as a very rough guide to be supplemented by eyes-on evaluation. That said, LCD contrast-ratio specs start at about 600:1, while those for plasmas start at about 1000:1 or better. Although ratings of 10,000:1 or better are becoming common for both types of displays, you should approach them with skepticism; whether any of them accurately reflect performance under real-world conditions is doubtful.
Important: Aspect Ratio

The aspect ratio describes the relationship of screen width to screen height. Conventional sets have a 4:3 aspect ratio, whereas wide-screen models are 16:9. Wide screens are the future. HDTV is a wide-screen format, for one thing. For another, DVDs usually look better on wide-screen displays because nearly every movie made in the last 50 years was filmed in an aspect ratio of either 1.85:1 (very close to 16:9, which is 1.78:1) or 2.35:1 (even wider than 16:9).
Important: Resolution

Non-CRT displays, such as plasmas and LCDs, are fixed-pixel arrays, which means they have rows and columns of individual picture elements that turn on and off to produce the necessary patterns of light. Resolution is specified as the number of pixel columns by the number of pixel rows--640 by 480, for example, or 1280 by 720. Resolution and, to a somewhat lesser degree, contrast ratio determine perceived picture detail.

Digital content currently is delivered in one of five formats: 480i, 480p, 720p, 1080i, and 1080p. The 480i format is the same as that used for standard analog TV, and when programming originally in 480i is delivered by digital cable or satellite to your home, it retains that format. DVDs are sometimes mastered in 480p, but mostly they are 480i; a progressive-scan DVD player can deinterlace 480i DVDs to create 480p output, however. The 720p and 1080i formats are used by satellite, cable, and over-the-air-broadcast high-definition content providers, as well as some advanced DVD players that upconvert 480i and 480p content. Blu-ray and HD-DVD discs carry 1080p video, though their corresponding players can deliver the content in 1080i or 720p format for displays that do not accept 1080p input.

Generally speaking, a display is considered high definition if it is wide screen and has a total pixel count approaching 1 million. So 1920 by 1080, 1280 by 720, 1366 by 768, and 1024 by 1024 are all examples of high-definition display resolutions. Small differences are not very consequential at greater than 1280 by 720, the specified resolution of the 720p high-definition format. Any resolution of 1280 by 720 or greater is best for viewing high-definition broadcast and DVD content; if you sit close to a large screen (50 inches or greater), you may prefer one of the new 1920 by 1080 (1080p) displays, but the increased picture detail afforded by such a high-resolution display will be difficult or impossible to see on a smaller screen unless you are sitting very close to it (less than 10 feet). Non-HD wide screen is called enhanced-definition; a typical ED resolution is 852 by 480. Standard-definition, or SD, includes 640 by 480 and 720 by 480. Enhanced-definition displays are better for 480p content such as that from progressive-scan DVD players.
Important: Video Inputs

The number and type of video inputs determine which sources you can use with the display.

Composite video: This input type has the lowest quality but the broadest compatibility. Any device that has video outputs will include composite video among them. Connection is made with a single 75-ohm coaxial cable between RCA jacks.

S-Video: S-Video offers better quality than composite video, and most video sources except standard VCRs now have S-Video outputs. Connection is made with a special cable and multipin sockets.

Component video: This high-quality option is the minimum standard for connecting HDTV tuners and progressive-scan DVD players. It requires three 75-ohm coaxial cables of the same type used for composite video.

RGB+H/V: This is another high-quality input type. An analog red-green-blue horizontal/vertical connection is sometimes used instead of component video. This input requires five 75-ohm coaxial cables of the same type used for composite video.

VGA: Video graphics array is a high-quality analog RGB connection used for computer connections and sometimes in place of RGB+H/V.

DVI: This is one of the highest-quality types of inputs. Digital visual interface is a digital video connection, commonly used for HDTV tuners and occasionally for DVD players; it may also be used for computer connections. Requires a special cable and multipin sockets. Some displays with a DVI input may work only with computers, so watch out for that if you plan to connect an HDTV source, such as an HD digital cable box or an HD DVD or Blu-ray Disc player. Another thing you need for guaranteed HDTV compatibility is compliance with the HDCP (High-bandwidth Digital Content Protection) system.

HDMI: Also of the highest quality, High-Definition Multimedia Interface is basically DVI plus a digital audio and control link, and it normally incorporates HDCP; it can be mated to DVI with adapter cables. This connection is provided in most current outboard HDTV tuners, HD satellite receivers, HD cable boxes, and upconverting DVD players, and it is the standard video connector for Blu-ray and HD DVD players.
Somewhat Important: Built-In Tuners

Most current flat-panel displays include a tuner for conventional analog broadcast and cable TV reception, and many have built-in broadcast HDTV tuners, as well. Some, however, are strictly displays, or monitors, with no built-in tuner (a more common setup for plasmas than for LCDs). That may not matter if you receive all your TV programming via satellite or cable, but if you want to watch broadcast TV over an antenna, be sure that the set you buy includes a TV tuner. Some sets also have built-in tuners for digital cable TV. Although such tuners have a standard for handling scrambled premium channels (for example, HBO), not all sets support it yet, so be sure you know exactly what you are getting. If you want that capability, make sure the set you buy has a CableCard slot and that your cable provider can provide you with the necessary electronic ID card.
Minor: Comb Filter Type

Comb filters are necessary in analog TV to separate color and luminance information without losing too much detail, but that's not an issue in HDTV. The only time the comb filter comes into play is for analog TV reception or any signal coming in via a composite video connection. For all other connections, it's out of the loop. Plus, the comb filters in all but budget CRT TVs are routinely very good these days.

Flat-Screen TV Shopping Tips

Flat-out ready to buy? Here are key points to consider before you make the big commitment.

Consider the alternatives: If you can live with a tabletop set that's 10 to 18 inches deep rather than 4 to 7, LCoS (liquid crystal on silicon) and DLP (digital light-processing) rear-projection sets can deliver performance approaching or exceeding that of plasmas in similar screen sizes and at lower prices. You just don't hear about them as much because they're not as sexy.

Think HDMI: If at all possible, you should get a set with an HDMI (High-Definition Multimedia Interface) input. This will ensure full compatibility with HDTV sources such as HD digital cable boxes, HD satellite receivers, and HD DVD and Blu-ray Disc players.

Compare displays using a variety of material: Just about any flat-panel display will handle HDTV and DVD signals well, but mediocre cable and satellite signals will give some of them fits. Don't make a buying decision based solely on pictures generated from pristine sources.

Look for good blacks: When you're comparison shopping, bring along a DVD of a movie containing some dimly lit night scenes. Use it to check for good black reproduction and ability to render detail in near-darkness.

Get to know the remote: A good remote can be your best friend, a bad remote your worst enemy. (Well, okay, we're exaggerating a little, but you get the idea.) Does it have backlighting or glow-in-the-dark buttons to help you see what you're doing when the lights are turned down? How easy is it to find commonly used buttons by feel?

Check the video settings: Now that you've got the remote, pull up the video-adjustment menu and look at the settings. If you thought the picture looked a little (or a lot) off on first viewing, try selecting the median settings for contrast, brightness, color, tint, and sharpness. Those probably won't be optimum, but chances are they're closer than what you found originally. A good display can easily look worse than a lesser one if it's poorly adjusted. Repeat your tests using a variety of sources, including a dimly lit movie, if necessary.

source: PC World, http://www.pcworld.com/article/125816-1/article.html