Dallasnews.com: On The Significance of Megapixels
I overheard a conversation between a camera salesman and another person where the former was recounting the many occasions where new camera buyers showed what he considered an unreasonable interest in the number of megapixels in the cameras on offer. He proceeded to explain the several other features which were of significance when considering the quality of a camera. This explanation on the DallasNews addresses the concern of megapixel significance and touches on related issues as well. 'Instead of capturing the optical image on film, a digital camera reads every tiny bit of light and describes its brightness and color in a computer file.
Those tiny bits are called pixels, short for picture elements. The smaller the pixel, the more detail in your photo. Multiplying the number of pixels across by the number of pixels down on the image-capture device inside your camera will tell you how many megapixels are in your image.'
Source: Dallas News