A slide is a single page of a presentation. A group of slides is called a slide deck. A slide show is an exposition of a series of slides or images in an electronic device or on a projection screen. Before personal computers, they were 35 mm slides viewed with a slide projector[1] or transparencies viewed with an overhead projector.
In the digital age, a slide most commonly refers to a single page developed using a presentation program such as MS PowerPoint, Apple Keynote, Google Slides, Apache OpenOffice or LibreOffice. Some are created with document markup language, such as the LaTeX-class Beamer. Lecture notes in slide format are lecture slides, frequently downloadable by students in .ppt or .pdf format.