A regular television with an interlaced screen has 525 scanned lines per image, and half of the picture is refreshed every 30th of a second. Only 480 of those lines are actually seen, though. A regular TV has the same qualities, but the entire image is refreshed at one time instead of only half.

Standard TV uses a 4:3 aspect ration, which looks almost like a perfect square. A high definition TV (HDTV) has 720 interlaced lines (720i), 1080i or 1080 progressive lines (1080p). HDTV also has the same aspect ratio of the average movie screen, 16:9.

This means that not only do HDTV’s have much clearer and crisper picture quality, but they also have a more accurate picture as well since the sides of the picture aren’t cut out. Another great thing about HDTV is the digital surround sound. HDTV’s can recreate 5.1 sounds. You can attach 5 different speakers and a sub-woofer to your TV.

This provides a highly superior sound compared to the one or two speakers on a regular television. There are two catches, however. If there is no HD programming in your area, your HDTV won’t look any better than your neighbor’s standard TV. Secondly, an HDTV must have an HDTV receiver. This can either be built-in or purchased separately.

Now that you have an idea of what HDTV is and how it differs from standard television you’re almost ready to purchase one. There are four types of HDTV screens to consider each one has both good and bad aspects about them. Deciding which one is right for you becomes very important at this point. Keep in mind that prices can vary widely.

Direct-view CRT (cathode-ray tube) TVs are very inexpensive, especially considering their HDTV quality. You can see them very well from most angles, and they produce the best black coloring on the market. Having good dark black coloring is necessary for creating a good picture. There are some weak points to owning a CRT TV to consider before buying one, though. CRTs are very bulky, which limits their size. It’s exceedingly rare to find one larger than 36″. They also have lower resolutions than other kinds of HDTV’s and usually can’t be used with your computer. Finally, CRT TVs don’t give a good picture in brightly lit rooms. These are an excellent choice if you’re on a budget or are looking for a nice second TV for the den.

The second type of HDTV is the flat-panel LCD. This is the most popular type of HDTV; this is partly due to the wide range of sizes available, their flat screens and similar pricing to CRT TVs in sizes up to 32″. Their flat viewing area also makes them good choices for well-lit rooms. Most flat-panel TVs are only a couple of inches thick, allowing them to fit almost anywhere. Their dark black coloring and viewing angles aren’t as good as some other types of televisions on the market, but their falling prices more than make up for this. LCD technology is progressing, however, and many of the larger, high-end models can give even the best TV a run for its money. If you have the money to plunk down on a high-end model, LCD might be a right choice. Holding out for a couple of years to allow technology to improve a little might not be a bad idea.

A close cousin of the LCD is the flat-panel plasma TV. Oddly enough in sizes, less than 50″ these TVs cost more than LCD versions. At 50″ or larger, plasma screens are much less expensive than their counterparts. These are often as thin as LCD’s but are even better for home theaters. Their extensive viewing angle makes them a better purchase than other technologies. Plasma TVs have excellent color saturation and resolution, but lower-end models have a small chance of burn-in. This can occur if images are left on the screen for a long time, like crawlers or stock tickers. The life span of plasma screens is a little shorter than other types of TVs with noticeable fading occurring at an average of 12-15 years. With falling prices and an ever-improving picture quality, plasma TVs are going to remain the best choice for home-theater viewing for the foreseeable future.

Here is a quick breakdown of LCD and plasma screens. LCD screen can range from 5 to more than 65 inches while plasma pretty much sticks to the wide end at 42 to over 65 inches. Inch for inch, LCD uses slightly less energy. 42″ screens are less expensive under 42″ while plasma is cheaper over 42″.

Most LCD models are PC compatible while plasma normally isn’t. Generally speaking, plasma screens have a slightly better picture than LCD, although different models may vary. Plasma screens have a much wider viewing angle than LCD but can suffer from worse glare. There is a small chance of burn-in with plasma, almost no chance with LCD.

Because if it’s better resolution, plasma tends to do better with DVD movies than LCD, the same holds true with games.

The final, and most confusing, type of HDTV is the rear-projection TV (RPTV). These are the big daddies of the viewing world. If you’re looking for anything over 50″, you’ll want to head over to the rear-projection center. There are some different technologies available with RPTVs so knowing what you’re getting into is important. Most of these technologies deal with microdisplays.

These kinds of televisions utilize microchips containing millions of pixels. The all provide excellent viewing but have to be replaced every few years. The chips can cost more than $200 but are easily replaced. Each of the major manufacturers uses a different kind of chip, and each produces a perfect picture. The best of these technologies are Digital Light Processing (DLP) and Liquid Crystal on Silicon (Lcos).

Now that you have an idea about what kinds of technology are available, there are a few other things to remember when you’re out looking for a new HDTV. The first thing is to make sure you’re getting HDTV and not EDTV, or enhanced definition TV). EDTV has the slightly better resolution the standard TV but nothing like HDTV.

Check out the TV you’re looking at to make sure it has a High-Definition Multimedia Interface (HDMI) port that will support 1080p and High-bandwidth Digital-content Protection (HDCP), so you’ll be able to use an HD-DVD or Blue-Ray DVD player. As an afterthought, the more connections you have, the better off you’ll be. This is especially true if you are planning to attach a lot of components to your TV, like video games. Without ports like these, you’ll be losing a lot of your the new television’s capabilities.

Different channels will send out different resolutions signals. Those messages range from 480p up through 1080p. A good HDTV will be able to view all of these broadcasts in the proper resolution. Make sure you find one that offers as many recommendations as possible. One thing to remember about HDTV is that when watching standard television, the picture may actually look worse. Having such a high resolution can sometimes produce over-pixilated pictures and distorted images.

Don’t forget that HDTV reproduces the movie theater atmosphere, including the sound. Having a great picture is only half of the experience. If you don’t have the speakers for it, I highly recommend getting them. Most department stores and electronic centers sell complete surround sound kits that include all the speakers you’ll need plus a DVD player. Once you have everything set up and pop in your favorite DVD, you’ll wonder how you ever lived without HDTV!