<P> Originally these programs were used to generate 35 mm slides, to be presented using a slide projector . As these programs became more common in the late 1980s several companies set up services that would accept the shows on diskette and create slides using a film recorder or print transparencies . In the 1990s dedicated LCD - based screens that could be placed on the projectors started to replace the transparencies, and by the late 1990s they had almost all been replaced by video projectors . </P> <P> The first commercial computer software specifically intended for creating WYSIWYG presentations was developed at Hewlett Packard in 1979 and called BRUNO and later HP - Draw . The first microcomputer - based presentation software was Cromemco's Slidemaster, developed by John F. Dunn and released by Cromemco in 1981 . The first software displaying a presentation on a personal computer screen was VCN ExecuVision, developed in 1982 . This program allowed users to choose from a library of images to accompany the text of their presentation . PowerPoint was introduced for the Macintosh computer in 1987 . </P> <P> A presentation program is supposed to help both the speaker with an easier access to his ideas and the participants with visual information which complements the talk . There are many different types of presentations including professional (work - related), education, entertainment, and for general communication . Presentation programs can either supplement or replace the use of older visual - aid technology, such as pamphlets, handouts, chalkboards, flip charts, posters, slides and overhead transparencies . Text, graphics, movies, and other objects are positioned on individual pages or "slides" or "foils". The "slide" analogy is a reference to the slide projector, a device that has become somewhat obsolete due to the use of presentation software . Slides can be printed, or (more usually) displayed on - screen and navigated through at the command of the presenter . An entire presentation can be saved in video format . The slides can also be saved as images of any image file formats for any future reference . Transitions between slides can be animated in a variety of ways, as can the emergence of elements on a slide itself . Typically a presentation has many constraints and the most important being the limited time to present consistent information . </P> <P> Many presentation programs come with pre-designed images (clip art) and / or have the ability to import graphic images, such as Visio and Edraw Max . Some tools also have the ability to search and import images from Flickr or Google directly from the tool . Custom graphics can also be created in other programs such as Adobe Photoshop or Adobe Illustrator and then exported . The concept of clip art originated with the image library that came as a complement with VCN ExecuVision, beginning in 1983 . </P>

List at least four possible purposes for an electronic presentation