The projector is the source of light in any projected display and is a major factor affecting image quality.
Most displays are created using video/data projectors. Slide projectors and film projectors are now rare and are not covered directly in this guide. However the basic principles still apply.
Video and data projectors today are extremely powerful and versatile, offering the potential of very high quality images.
Current projector technologies share the same basic principle: using some kind of image-producing element which is projected through an optical system, namely the lens.