A projector is an output device that can take images generated by a computer or Blu-ray player and reproduce them onto a screen, wall, or other surface. Typically, the surface projected onto is large, flat, and lightly colored. For example, you could use a projector to show a presentation on a large screen so that everyone in the room can see it. Projectors can produce either still (slides) or moving images (videos). A projector is often about the size of a toaster and weighs only a few pounds.