Compared A digital camera with 640 x 480 resolution is supposed to be good for pictures to post on the web. I know what I need to put pictures on the web. I don't need accurate color, because I have software that can do color correction, but I need pictures that don't look fuzzy when dimensioned at 640 x 480 and posted on the web. Cameras that claim 640 x 480 resolution are not all alike. I call that the dimensions of the picture, not the resolution.
Resolution refers to how well details are resolved.
The standard test for cameras that use film is to take a picture of various sets of black lines separated by white spaces of the same width as the lines. Different sets of lines have different widths, and the width of the narrowest lines you can see on the film, expressed in lines per millimeter, is called the resolving power of the lens and film together. If the film is much better than the lens, then what you get is called the resolving power, or resolution, of the lens. But there is still another difference. A CCD with 640 x 480 pixels has exactly 300K pixels.