What is the difference between plasma, lcd, and hd tvs?

W_robrecht’s answer has some great information. I just thought I’d add a few things, if I may. If you’re looking for the “best deal”, I would also recommend you check out some of the rear projection HDTVs. If you weren’t already familiar with those, let me explain: There are two ways to create images on a TV. One is to create a small image and project it onto a screen (think of old photo slides), or you can just create the image right on the screen. Plasma and LCD flat panels are examples of image creation directly on the screen, which allows it to be ultra-thin (3"-4"). They are also believed to create the most vibrant and high-contrast images. On the downside, they are the most expensive formats and plasma TVs do suffer from a bit of glare issue in bright conditions. It’s because plasma TVs have to use glass screens (you are dealing with actual plasma after all). Which also makes them much heavier than a comparable sized LCD TV (but really, who cares about the weight, right?). Of course, there are other flat panel technologies such as: SED (Surface-conduction Electron-emitter Display) and OLED (Organic Light Emitting Diode). But they may still be months or years away and will likely be cost prohibitive for the most of us for the near future. However, if you don't mind a little added thickness (12"-20" in depth), projection types can offer you a huge savings compared to the flat panels. LCD technology can be found here as well. Instead of creating a huge image directly on the screen, a smaller LCD image is created behind the TV, then a beam projects the image onto the screen. DLP (Digital Light Processing) works almost the same way, except instead of beaming a light through an image like a "slide" as with LCDs, a DLP chip consisting of thousands of micromirrors reflects the beam in different directions to create the image. Amazing, right? Some of the drawbacks with both formats are that they aren't as bright and high contrast as plasmas or flat panel LCDs. Also, LCDs can have what's called a "screen door" effect when up really close (like looking through a screen door where you can see a grid pattern) and DLPs can display a "rainbow effect" (color separation because the image created by the micromirrors are just black and white and thus have to go through a “color wheel”) although most people won't be able to notice. Resolution figures are pretty straightforward. Higher the better (with 1080 being the highest), and "p" (progressive) is better than "i" (interlaced). HDTV, by the way is anything 720 or better. 1080p (full HD) is currently the highest definition format (Blu-Ray discs and HD-DVD), but most HD cable and satellite channels broadcast in 1080i or 720p. For comparison, regular DVD images which amazed us just a few years ago is only in 480p. One last thing, there's more to HDTVs than what's explained here. A 50" plasma with 1080p resolution from one manufacturer is not the same as another from a different manufacturer. The image processors or built-in software as well as other things hidden inside the TV can make all the difference. That's likely why a no-name brand can sell their plasma TVs for half the price of a Sony, Samsung or Philips. If possible, stick with the recognizable brands and go to a local BestBuy and check out the actual model. Beauty, after all is in the eye of the beholder. You may find that you prefer the picture of certain brand over another. Good luck and enjoy. My HDTV is one of the best investments I’ve ever made. Programs on Discovery HD channel will blow you away. Addition: AWolf, you're absolutely right. I would never suggest going to BestBuy (or any brick & mortar store) to get the best deal. Much better deals can be had online (at such bargain finder sites as dealnews.com or techbargain.com, couple of my favorite sources). I merely meant before one decides on a purchase, one should go to a store and check out the actual picture. It's something you can't do by just reading the descriptions or tech specs.