How are all cameras basically the same?

All cameras share these general characteristics: A light-tight box to contain a photo-sensitive medium A medium sensitive to light and capable of reacting to light in proportion to its variations in brightness. This can be photographic film, paper, or an electronic sensor such as a CCD. A means of projecting an image onto the medium (usually a lens) Some means of controlling the time of exposure (shutter) Some means of controlling the overall brightness of the light reaching the medium (variable lens aperture) In many applications, but not all, some means of viewing the image to be captured.