Definition…

The term “pixel” is actually short for “Picture Element.” These small little dots are what make up the images on computer displays, whether they are flat-screen (LCD) or tube (CRT) monitors. The screen is divided up into a matrix of thousands or even millions of pixels. Typically, you cannot see the individual pixels, because they are so small. This is a good thing, because most people prefer to look at smooth, clear images rather than blocky, “pixelated” ones. However, if you set your monitor to a low resolution, such as 640×480 and look closely at your screen, you will may be able to see the individual pixels. As you may have guessed, a resolution of 640×480 is comprised of a matrix of 640 by 480 pixels, or 307,200 in all. That’s a lot of little dots.

Each pixel can only be one color at a time. However, since they are so small, pixels often blend together to form various shades and blends of colors. The number of colors each pixel can be is determined by the number of bits used to represent it. For example, 8-bit color allows for 2 to the 8th, or 256 colors to be displayed. At this color depth, you may be able to see “graininess,” or spotted colors when one color blends to another. However, at 16, 24, and 32-bit color depths, the color blending is smooth and, unless you have some kind of extra-sensory vision capability, you should not see any graininess.

Definition of: blown pixel

A defective pixel on an LCD screen. Bad pixels are often transistors that are permanently dead and appear as black dots or permanently energized and show up as white or colored dots (“hot pixels”). These pixel defects usually occur at the time of manufacture. However, if a bad pixel appears after the screen has been in use for some time, it may also be due to a dented or scratched polarizer (see LCD).

Sometimes, it is possible to repair a bad pixel by gently rubbing the screen with a cloth or running a pixel repair over the area for several hours, the latter repetitively flashing colors on and off to attempt to dislodge a stuck pixel.

Source: http://www.pcmag.com encyclopedia