A Charge-Coupled Device (CCD) is a light-sensitive integrated circuit that stores and displays the data for an image in such a way that each pixel (picture element) in the image is converted into an electrical charge the intensity of which is related to a color in the color spectrum.
CCDs are now commonly included in digital still and video cameras.
A CCD in a digital camera improves resolution compared with other technologies (such as CMOS).
Another asset of the CCD is its high degree of sensitivity. A good CCD can produce an image in extremely dim light, and its resolution does not deteriorate when the illumination intensity is low, as is the case with conventional cameras.
Pro's & Con's
CMOS chips are less expensive to manufacture, and that cost savings translates into lower camera prices.
CMOS chips perform better than CCD chips when capturing highlights, such as the sparkle of jewelry or the glint of sunlight reflecting across a lake.
The main argument in favor of CCD chips is that they're more sensitive than CMOS chips, so you can get better images in dim lighting.
CCD chips tend to deliver cleaner images than CMOS chips, which sometimes have a problem with noise (small defects in the image).
CCD chips suffer from blooming, which means creating unwanted halos around very bright highlights, while CMOS sensors do not.