Aspect ratio:
The standard proportion in width to height for a computer monitor is 4:3, but some new displays have a wider format: 16:9 or 16:10, designed for viewing movies or HDTV in wide format. Note that a 17-inch wide-format panel has about the same vertical dimension and vertical pixel count as a normal 15-inch panel, so you get about 120 percent of the viewing area of a 15-inch panel. A 17-inch standard panel, however, has 130 percent of the viewing area of a standard 15-inch screen.

Contrast ratio:
A spec much hyped by manufacturers (be suspicious of their claims), this is the difference in light intensity between the brightest white and the deepest black.

1. Dynamic contrast ratio
   A notable recent development in the LCD technology is the so-called “dynamic contrast” (DC). When there is a need to display a dark image, the display would underpower the backlight lamp (or decrease the aperture of the projector’s lens using an iris), but will proportionately amplify the transmission through the LCD panel. This gives the benefit of realizing the potential static contrast ratio of the LCD panel in dark scenes when the image is watched in a dark room. The drawback is that if a dark scene does contain small areas of superbright light, image quality may be over exposed.The trick for the display is to determine how much of the highlights may be unnoticeably blown out in a given image under the given ambient lighting conditions.
   Brightness, as it is most often used in marketing literature, refers to the emitted luminous intensity on screen measured in candela per square metre (cd/m2). The higher the number, the brighter the screen.
   It is also common to market only the dynamic contrast ratio capability of a display (when it is better than its static contrast ratio), which should not be directly compared to the static contrast ratio. A plasma display with a static 5000:1 contrast ratio will show superior contrast to an LCD with 5000:1 dynamic and 1000:1 static contrast ratio when the input signal contains a full range of brightnesses from 0 to 100% simultaneously. They will, however, be on-par when input signal ranges only from 0 to 20% brightness.
2. Contrast ratio in a real room
   In marketing literature, contrast ratios for emissive (as opposed to reflective) displays are always measured under the optimum condition of a room in total darkness. In typical viewing situations the contrast ratio is significantly lower due to the reflection of light from the surface of the display, making it harder to distinguish between different devices with very high contrast ratios. How much the room light reduces the contrast ratio depends on the luminance of the display, as well as the amount of light reflecting off the display. A clean print at a typical movie theater may have a contrast ratio of 500:1 Dynamic contrast ratio is usually measured at factory with two panels (one vs another) of the same model as each panel will have an inherent Dark and Light (Hot) spot. Static is usually measured with the same screen showing half screen full bright vs half screen full dark. This usually results in a lower ratio as brightness will creep into the dark area of the screen thus giving a higher luminance.

Luminance:
Brightness; Luminance is thus an indicator of how bright the surface will appear. In this case, the solid angle of interest is the solid angle subtended by the eye’s pupil. Luminance is used in the video industry to characterize the brightness of displays. A typical computer display emits between 50 and 300 cd/m².

Pixel-response rate:
This refers to how quickly a pixel can change colors, measured in milliseconds (ms); the fewer the milliseconds, the faster the pixels can change, reducing the ghosting or streaking effect you might see in a moving or changing image. In general, manufacturers’ specifications rely on best-case scenarios; real-world performance could be slower. A maximum of a 12ms-to-15ms response time across the spectrum is required for gaming or viewing television and movies without ghosting or streaking.

Resolution:
is the number of distinct pixels in each dimension that can be displayed.
Make sure you are comfortable with an LCD’s native resolution. Remember, an LCD that scales its image to a nonnative resolution will never look as good.

Viewing angle:
is the maximum angle at which a display can be viewed with acceptable visual performance.The physical structure of LCD pixels can cause the brightness and even the color of images to shift if you view them from an angle rather than facing the screen directly.

Refresh rate:
is the number of times in a second that a display is illuminated. Maximum refresh rate is limited by response time.

Response time:
is the time a pixel in a monitor takes to go from active (black) to inactive (white) and back to active (black) again, measured in milliseconds. Lower numbers mean faster transitions and therefore fewer visible image artifacts.