From ECDL.web

A liquid crystal display (LCD) is a thin, flat electronic visual display that uses the light modulating properties of liquid crystals (LCs). They are used in a wide range of applications, including computer monitors, television, gaming devices, clocks, watches, calculators, and telephones. LCDs have displaced cathode ray tube (CRT) displays in most applications. They are usually more compact, lightweight, portable, less expensive, more reliable, and easier on the eyes.

As LCD panels produce no light of their own, they require an external lighting mechanism. On most displays, this consists of a cold cathode fluorescent lamp that is situated behind the LCD panel. Recently, LED backlit LCD displays have appeared in some televisions as an alternative to conventional backlit LCDs. LED backlighting allows for a slimmer panel than on conventional LCDs.

Specifications

• Resolution: the resolution of an LCD is expressed in terms of the number of columns and rows of pixels (e.g., 1024×768). Each pixel is usually composed of a red, green, and blue sub pixel.
• Aspect ratio is the ratio of the width to the height of the monitor (for example, 4:3, 5:4, 16:9 or 16:10). Older, standard definition TVs and monitors were 4:3. Newer LCD monitors are 16:9 as are most new notebook computer screens. Movies are often filmed in much different (wider) aspect ratios which is why there will frequently still be black bars at the top and bottom of the screen.
• The viewing angle of an LCD may be important depending on its use or location. The viewing angle is usually measured as the angle where the contrast of the LCD falls below 10:1. At this point, the colours usually start to change and can even invert. Viewing angles for LCDs used to be very restrictive however, improved optical films have been developed that give almost 180 degree viewing angles from left to right. Top to bottom viewing angles may still be restrictive, by design, as looking at an LCD from an extreme up or down angle is not common.
• The refresh rate of an LCD is the number of times per second in which the display draws the data it is being given. Since activated LCD pixels do not flash on/off between frames, LCD monitors exhibit no refresh-induced flicker, no matter how low the refresh rate.
• Colour depth or colour support is sometimes expressed in bits, either as the number of bits per sub-pixel or the number of bits per pixel. For example, 8-bit in common terms means 2⁸ or 256 colours. 8-bits per colour or 24-bits would be 256x256x256 or over 16 million colours.
• Brightness and contrast ratio. Brightness is usually stated as the maximum output of the LCD. With current LCD technology, brightness, though important, is usually the same from maker to maker. In general, brighter is better but there is always a trade-off between brightness and battery life, for example in a mobile device. Contrast ratio is the ratio of the luminance of the brightest color (white, full-on pixel) to that of the darkest color (black, full-off pixel) that the monitor is capable of producing. A high contrast ratio is a desired aspect of any display.