What is the difference between LED, LCD and Plasma TV?

Buying a television should be fun and exciting, but for most, the process is anything but. The technology is advancing too fast for most of us to keep up, and the sheer amount of choice is overwhelming. Walk into a shop looking for a 32-inch LCD TV, you'll find at least a dozen models that all look alike, and you'll be beset by salespeople trying to sell extras, like a TV DVD combi and digital TV recorders. In order to help you keep focus and find that right television for sale, we've compiled these helpful points.
LED vs. LCD vs. Plasma
Outwardly, all three styles look very much alike. The differences are internal. Plasma technology employs electrically charged gas that strikes red, green, and blue phosphors to create the TV colours. LCD, on the other hand, uses individual liquid crystals that can block light or allow it to pass through. These crystals do not create their own light. A traditional LCD set uses a fluorescent bulb. An LED TV is an LCD that uses light-emitting diodes (LEDs) rather than a fluorescent bulb. 
Contrast Ratio
This is the TV's ability to display an image's full range. This is particularly important for making fine details visible in high contrast areas of the screen. One advantage plasma has over LCD is its ability to deactivate the light source, which produces better contrast. LED is an improvement over traditional LCD because it can as well.
Viewing Angle
As the viewer's eye angle to the TV set becomes greater than or less than 90 degrees, there is loss of contrast and colour. Plasma sets have wider viewing angles than LED, which are in turn better than LCD.
Colour
In theory, plasma produces brighter colours than LED, which produces brighter colours than LCD.

However, this is mostly a marketing point. In practice, there is very little difference, and the quality of the colour has much more to do with the quality of the set than the particular technology.
Motion
The motion capability of a television is important, especially for sports fans. If you have a low refresh rate and a lot of on-screen motion, the result will have blurring and jittering. The good news is that both plasma and LCD/LED are available in 100Hz. There are also 200Hz sets, but the benefit here is minimal.
Lifespan
Marketing makes a big deal of lifespan because they're trying to one up the competition. The truth is that most plasma and LED TV sets last 100,000 hours, which is 10 years even if the set is on 24/7. Traditional LCD sets are generally 60,000-100,000 hours.
Screen Size
Decide what size you want, and if it's less than 42 inches, go LCD or LED. Plasma is just too expensive at those smaller sizes. At the larger sizes, plasma and LED sets are at competitive prices. LCD sets can be as much as 20% less expensive, which makes it a good target for bargain hunters.