A lantern slide is a transparent image, typically made of glass, that is used in a projector to display pictures. These slides were popular in the 19th and early 20th centuries for educational and entertainment purposes. They often featured photographs, illustrations, or artwork and were illuminated from behind to project the image onto a screen. The use of lantern slides was common in settings like classrooms and public lectures, where they helped convey information visually. The technology evolved into modern projectors, but lantern slides remain a significant part of the history of visual media, influencing the development of tools like film projectors and digital presentations.