A "slide projector" is a device used to display photographic slides onto a screen or wall. It typically consists of a light source, a lens system, and a mechanism for advancing the slides. When the slides are inserted into the projector, they are illuminated by the light source and projected through the lens onto a surface, creating an enlarged image. The slides can be changed manually or automatically to display different images or a sequence of pictures. Slide projectors were commonly used before the advent of digital projectors and offer a nostalgic way to view and share photographic memories.