The Difference Between LCD, LED, Plasma Monitor

LCD (Liquid crystal Display) uses a solid florescent back light to light up individual pixels in different ratios between red, green, and blue to get your colors. The color black is achieved by blocking the light in a certain pixel, but the problem here is that you can never get true black with LCD screens because there is still a light on behind it making the color actually more of a charcoal gray. When electrical current flows through the liquid, the crystals move, and the polarized glass allows certain wavelengths of light from the bulb to pass through. This creates thousands of tiny dots, or pixels, of color that ultimately make up the picture on an LCD TV.

LEDs (light-emitting diodes) have been around for decades, but their introduction into TV design is a fairly recent development. LED televisions employ standard LCD technology but with one crucial difference – the handful of backlight lamps that traditionally illuminate the LCD screen are replaced by a larger number of tiny LEDs. This enables LED TVs to be much slimmer than their LCD counterparts.

Plasma tvs work differently.  Plasma TVs were developed in response to the weaknesses of LCD displays. Like LCD displays, a plasma screen TV has two panes of glass that make up the flat screen. Rather than using liquid crystals, plasma TVs have chambers filled with xenon and neon. When electricity runs through these chambers, the gas converts into plasma; as the plasma moves through the chamber, it emits photons that display in various colors.

The pros and cons to each LCD and Plasma are: 

LED (Light-Emitting Diode)

Pros	Cons
Superb picture quality	Quite expensive
Slimmer than other TVs	As it's slimmer, you lose  sound quality
Considerably lower power  consumption
Can be viewed from more  angles than an LCD
Has a long lifespa

LCD (Liquid Crystal Display)

Pros	Cons
Reasonable prices	Poor viewing angles, so you're restricted to how high you can place it
Comes in a variety of different  sized screens	Average lifespan is 60,000 - 80,000  hours of viewing
Less chance of pixel burn-out  than Plasma TVs	Slow response times means the picture  on the screen will take longer to update
Brighter image and a cooler  running temperature
Lightweight

Plasma

Pros	Cons
Great range of larger sized screens	Average TV lasts around 60,000 - 80,000  hours of viewing time
Can view the screen from high  angles	Prone to pixel burn out, which can be too  pricey to fix
Fast pixel response time, giving you  a clearer picture. Especially when watching live,  fast-paced shows	Hefty power consumption
Newer models are becoming more  reliable

nowadays, many people buy LED TV. Given the dwindling availability of LCD TVs and the ongoing demise of plasma TVs, most TV buyers will go for an LED set, and that’s no bad thing considering that they're getting a slim and energy-efficient television.
However, bear in mind that picture and sound quality on LED TVs varies hugely between brands and models. Be sure to check the best LED TV to ensure you make the right buying choice.



source :
http://technicallyeasy.net/2011/04/differences-between-lcd-plasma-and-led-televisions/
http://knowhow.com/article.dhtml?articleReference=920