A megapixel (that is, a million pixels) is a unit of image sensing capacity in a digital camera. (A pixel - a word invented from "picture element" - is the basic unit of programmable color on a computer display or in a computer image.) In general, the more megapixels in a camera, the better the resolution when printing an image in a given size. A digital camera with a 1.3 megapixel resolution will print a good quality 4 x 3 inch print at 300 dpi (dots per inch). If a higher quality is needed or a larger print at the same quality, a camera with a higher megapixel value will be needed.
The number of images that can be stored in a given size of flash memory for the camera is determined by the size of the flash memory and the size of each image in terms of megapixels.