A slide show is a display of a series of chosen information, and/or pictures, which is done for artistic or instructional purposes. Slide shows are conducted by a presenter using an apparatus, such as a carousel slide projector, an overhead projector or in more recent years, a computer running presentation software. The term "slide" originates from the use of slides which have been around for many years. Slides originally were projected on a screen, for example in a theater by magic lanterns, a practice that later evolved into moving picture shows. Even after the advent of motion pictures, slides continued to be employed for a time between showings of the films, especially to advertise local businesses or maintain theater decorum -- for example by requesting that gentlemen remove their hats and refrain from smoking, and urging mothers to remove crying infants from the auditorium.
The earliest slides were pieces of glass carrying photographic images, and later, pieces of photographic film sealed between two thin sheets of glass. Projectors had a frame mechanism which accommodated two of the sealed photos and was moved from left to right to left, bringing one slide between the lens and the light source, while a "next" photograph was inserted into the frame, alternately from the left or right side of the projector. The image medium itself came to be called a "slide." The black-and-white images were sometimes hand-tinted. With the widespread availability of color film in the 1940's the large, cumbersome and fragile glass slides were replaced by individual pieces of 35 mm color film bonded between two thin 2-by-2-inch cardboard frames. The Kodak Carousel projector accommodates some 80 of these frames in a doughnut-shaped slotted plastic container and has a motorized mechanism to drop and retrieve each slide sequentially on an electronic command of a "remote" button device held by the projectionist as the circular carrier advances above the lamp and lens of the machine.
A well organized slide show allows a presenter to fit visual images to an oral presentation. The old adage "A picture is worth a thousand words" holds true, in that a single image can save a presenter from speaking a paragraph of descriptive details. As with any public speaking or lecturing, a certain amount of talent, experience, and rehearsal is required to make a successful slide show presentation.
Presentation software is most commonly used for instructional purposes, usually with the intention of creating a dynamic, audiovisual presentation. The relevant points to the entire presentation are put on slides, and accompany a spoken monologue.
Slide shows have artistic uses as well, such as being used as a screensaver, or to provide dynamic imagery for a museum presentation, for example, or in installation art. David Byrne, among others, has created PowerPoint art.