Our television viewing habits are changing thanks to techology, from personal video recorders to streamed internet video, but the sets we use to view our favourite shows have undergone nothing short of a wholesale revolution (retail, too, as prices have plunged).

Analog may have been good enough for TV's first 50 years. But now the new standard is digital and it's HDTV that's capturing all the attention. It's out with the CRTs and in with the LCDs and DLPs and plasmas. But what do all these initials mean?

First, a look at the technology behind the screens. Thick old TV cubes – a shape dictated by the need for a cathode ray tube (CRT) to beam electrons on to a phosphorescent screen — are all but gone from the retail scene. These days, thin (or at least, thinner) is clearly in.

And when it comes to thin flat panel TVs, consumers have two main choices: LCD or plasma.

LCD Sets

LCD (Liquid Crystal Display) technology is one of the most popular of the newer TV technologies. Polarized light is shone through a panel of liquid crystals that are sandwiched between two glass plates. LCD flat panel TVs are lightweight, use very little power, are not susceptible to burn-in, and have a higher resolution than plasma sets of the same size because they have smaller transistors.

They're often slightly thinner than plasma sets of the same screen size. LCD screens are available in either a 16:9 aspect ratio (just like the movies) or in a 4:3 ratio (which conventional TV uses).

On the minus side, LCDs tend to be less forgiving than plasma sets when viewed at an extreme angle (although the newest sets have reportedly closed that gap) and plasma sets display deeper blacks and have better contrast. Unlike plasma TVs, LCDs are available in screen sizes as small as 13 inches.

Plasma Sets

The screeen in a plasma TV uses a matrix of thousands of gas plasma bubbles. When the juice is turned on, some of the plasma bubbles give off ultraviolet rays that cause a phosphor coating to glow. The colours produced can be among the richest and most vivid produced by any TV set.

The most expensive hang-on-the-wall sets are typically plasma. Plasma screens all use the widescreen 16:9 aspect ratio, so if you're watching conventional TV (which uses a 4:3 ratio), you'll either get black bars on the sides or the set can "stretch" the picture to fill the whole screen.

Plasma sets use more electricity, usually weigh a bit more, and are a little thicker than LCD sets of the same size. The pixels in a plasma screen are prone to burn-in, but that's not an issue with normal channel-surfing. They don't come in screen sizes smaller than 32 inches or so.

DLP Sets

DLP sets were the latest thing a couple of years ago, but these days they've been eclipsed by plasma and LCD.

One reason is convenience — you can't hang DLP sets (Digital Light Processing) on the wall. As the name suggests, light is processed digitally with the help of an optical semiconductor made up of more than a million tiny mirrors. These sets are available in either front or rear projection varieties.

The rear projection models have a smaller "footprint" than conventional cathode-ray-tube TVs of the same screen size, but are still considerably thicker than LCD or plasma sets. They are generally not available in sizes smaller than 40 inches or so.

DLP sets are not susceptible to burn-in, but like projectors, the bulb needs to be replaced every few years at a cost of around $250. The DLP picture is typically bright and crisp, but some reviewers give the nod to plasma and LCD sets on overall performance.

What about HDTV?

Once you've decided on what kind of new TV format you want, you have another decision to make. Do you want a model that can show programs in true high definition?

High-definition television images have more than twice the resolution of standard analog sets. The result is a picture that is much sharper than analog television. HDTV sets produce a picture that has 720 or 1080 scanned lines, versus the 480 lines of analog sets. HD signals also deliver CD-quality sound. All HDTV signals are digital. But not all digital TV is HDTV.

Enhanced Definition Television (EDTV) sets are digital, but are not high def. EDTV sets can play HD programming, but at a lower resolution that HD sets.

Sets that are marketed as being HDTV-ready aren't capable of displaying HD signals pictures unless you also have a separate high-definition set-top box. Most cable companies and satellite providers rent or sell the boxes. Be sure to find out if a separate box is necessary for the set you're buying.

More than two dozen high-definition channels are available in Canada, depending on the provider (including English and French offerings from the CBC). Eventually, all broadcasters in North America will make the transition from analog to digital over-the-air television broadcasting. The CRTC has established Aug. 31, 2011  as the date when Canadian broadcasters must make the switch from analog to digital TV broadcasting (in the U.S., the date is June 12, 2009).