A photographic film is an encased roll of celluloid, a thin plastic sheet. Both sides of this celluloid are treated with special chemical blends. one side is coated with chemicals that aid the development of film negatives, while the other is coated with multiple layers of chemicals that help to form the images that eventually become photographs.
the chemicals Coatings that allow the creation of images on film are predominantly made up of silver halide crystals. When the shutter of the camera is pressed, light waves are reflected off the objects in front of the lens, and these are absorbed by the silver halide particles on the surface of the film. Then the film is developed, and treated with a chemical solution to 'fix' the film, so that it is no longer sensitive to light. What is now obtained is a negative image of the object, in which the light areas are dark, and the dark areas appear light. film negatives have long shelf lives, and can be used multiple times to create original photo prints.