What is Slide Film?
35mm slides are specially mounted individual transparencies intended for projection onto a screen using a slide projector. The most common form was the 35mm slide, with the image placed in 2x2" plastic or cardboard mounts and made from reversal type film. Reversal films produce positives on transparent bases rather than negatives or prints; 5-inch square pieces of such photographic material were called "diapositives".