LCD monitors
The liquid crystal display (LCD) technology now used in flat panel monitors is a device (also called a cell) made out of two layers of very fine glass material called substrates that form a "sandwich" around a thin layer of rod-shaped molecules (liquid crystals) that flow like liquid. When a charge of electric current passes through the layer of liquid crystals, they align or twist, preventing or allowing the light to pass through.

Resolution:
Make sure you measure the maximum true resolution--the resolution achieved by the number of pixels the monitor contains--without scaling the screen contents up or down.   Typical resolutions are:
1024x768 (XGA)  or 1280x1024 (SXGA)   or 1600x1200 (UXGA)
1280x720 (720p)   1280x768 (WXGA)      1366x768 (WXGA)   1920x1080 (1080i)

Size:
Size is measured diagonally from one corner of the glass to the opposite corner.   Typicall sizes are 15”, 17”, 19”,  21”, 26”, 32”, 40”, 42”, 46”, 50”, 52”, 60”, 62”, 70”, 82”

Aspect ratio:
This is related to resolution; it is the ratio of the monitor's width to height.
Most displays have a 1.25:1 ratio. Some have a wider format, 1.6:1 ratio. The amount of horizontal space is critical in determining how much information can be displayed at once, particularly when viewing side-by-side pages, or spreads.

Dot pitch:
This is a measure of the amount of space between each pixel. The smaller the dot pitch, the sharper the image.
The dpi, or dots per inch (also called pixels per inch), is related to dot pitch: the smaller the dot pitch, the higher the dpi is.

Brightness:
Brightness is determined by the intensity and quality of the backlighting; in displays, it is usually measured in luminance (candelas per square meter). A brighter monitor will be easier to view and have greater color intensity.

Color resolution:
The number of colors that can be represented on a display without dithering. Higher quality LCDs have 24-bit color, allowing a color gamut, or range, of 16.7 million.

Contrast:
Related to brightness, this is a measure of the range between the lightest tones and the darkest tones that the LCD is capable of producing. A higher contrast ratio makes the information on the display more readable.

Viewing angle:
This determines how far above, below, or to either side of the display a person can be and still accurately view the image on it. Typical viewing angles are from 150 to 178 degrees.

Response rate:
Measured in milliseconds or microseconds, this is the time it takes for a pixel to respond to voltage (to be turned "on") and then return back to its normal state. The shorter the pixel response rate, the more quickly the panel will be able to display and refresh images.

Difference between resolution and size
Resolution usually refers to pixel resolution, or the number of addressable pixels on a display, whereas size is a measure of the diagonal distance from one corner of the display glass to the opposite corner.  Even very small details in data or images appear very crisp, and a greater number of pixels allows users to comfortably display more information at once.

Pixel defects
Each graphic pixel on an LCD screen is made up of red, green, and blue sub-pixels. Due to the variables inherent to the manufacturing process, some of these sub-pixels become stuck in either the on or the off state. This pixel defect, also called a stuck pixel, appears as a small red, green, or blue dot for stuck-on pixels, or a small black dot for stuck-off pixels. During the manufacturing testing process, LCD panels that exceed a specified number of stuck pixels are rejected. In order to provide the latest flat panel technology at a reasonable price, LCD manufacturers allow a small number of pixel defects in their quality-control specifications., fewer pixel defects allowed with every new generation of displays and a zero-defect policy today would be prohibitively expensive. Even though TG flat panel displays have some of the strictest specifications for pixel defects in the industry.