CRT:

The cathode ray tube (CRT) is a vacuum tube containing an electron gun (a source of electrons) and a fluorescent screen, with internal or external means to accelerate and deflect the electron beam, used to form images in the form of light emitted from the fluorescent screen. The image may represent electrical waveforms (oscilloscope), pictures (television, computer monitor), radar targets and others.


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TFT

A thin-film transistor (TFT) is a special kind of field-effect transistor made by depositing thin films of a semiconductor active layer as well as the dielectric layer and metallic contacts over a supporting substrate. A common substrate is glass, since the primary application of TFTs is in liquid crystal displays. This differs from the conventional transistor where the semiconductor material typically is the substrate, such as a silicon wafer.


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LCD

A liquid crystal display (LCD) is an electro-optical amplitude modulator realized as a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector. It is often utilized in battery-powered electronic devices because it uses very small amounts of electric power.


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Pixel

Short for Picture Element, a pixel is a single point in a graphic image. Graphics
monitors display pictures by dividing the display screen into thousands (or millions) of pixels, arranged in rows and columns. The pixels are so close together that they appear connected.
The number of bits used to represent each pixel determines how many colors or shades of gray can be displayed. For example, in 8-bit color mode, the color monitor uses 8 bits for each pixel, making it possible to display 2 to the 8th power (256) different colors or shades of gray.
On color monitors, each pixel is actually composed of three dots -- a red, a blue, and a green one. Ideally, the three dots should all converge at the same point, but all monitors have some convergence error that can make color pixels appear fuzzy.
The quality of a display system largely depends on its resolution, how many pixels it can display, and how many bits are used to represent each pixel. VGA systems display 640 by 480, or about 300,000 pixels. In contrast, SVGA systems display 800 by 600, or 480,000 pixels. True Color systems use 24 bits per pixel, allowing them to display more than 16 million different colors.


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DPI measurement in video resolution:

Dots per inch (DPI) is a measure of spatial printing or video dot density, in particular the number of individual dots that can be placed within the span of one linear inch (2.54 cm.) The DPI value tends to correlate with image resolution, but is related only indirectly.

Because color display units use three coloured sub-pixels (red, green and blue) per pixel, the DPI measurement is frequently misused, especially in the automotive market. An example of misuse would be if an LCD monitor manufacturer claimed that a 320x240 pixel 3" monitor (2.4"x1.8") actually had a resolution of 400 DPI, (three times the pixels per inch). Technically this would be correct (as each sub-pixel could be considered a dot), but compared to the standard accepted practice of using pixels as a means of measuring resolution, it could mislead customers into thinking the relabeled monitor had a greater resolution and therefore better picture quality than identical but normally labeled monitors. Such misuse is commonly found in advertising for in-car LCD displays.

A less misleading term, therefore, is pixels per inch. Video displays are almost universally rated in dot pitch, which refers to the spacing between the sub-pixel red, green and blue dots which make up the pixels themselves. Very often, DPI is confused with image size, leading to expressions such as "1024 x 768 DPI XGA."