In photography, one is concerned only with the brightness or irradiance distribution (square of the amplitude) of the image. The optical path to different parts of the object is not recorded as the photographic emulsion is a square law detector and records only the amplitude.In holography, the aim is to record complete wave field (both amplitude and phase) as it is intercepted by a recording medium. The recording plane may not be even an image plane. The scattered or reflected light by the object is intercepted by the recording medium and recorded completely in spite of the fact that the detector is insensitive to the phase differences among the various parts of the optical field.

Holography is the science of producing holograms. It is a technique that allows the light scattered from an object to be recorded and later reconstructed so that it appears as if the object is in the same position relative to the recording medium as it was when recorded. The image produced changes as the position and orientation of the viewing system changes in exactly the same way is if the object were still present.

The technique of holography can also be used to optically store retrieve, and process information. It is common to confuse volumetric displays with holograms, particularly in science fiction works such as Star Trek, Star Wars, Red Dwarf, and Quantum Leap. Holography was invented in 1947 by Hungarian physicist Dennis Gabor (Hungarian name: Gábor Dénes) (1900–1979), work for which he received the Nobel Prize in physics in 1971. It was made possible by pioneering work in the field of physics by other scientists like Mieczysław Wolfke who resolved technical issues that previously made advancements impossible. The discovery was an unexpected result of research into improving electron microscopes at the British Thomson-Houston Company in Rugby, England. The British Thomson-Houston company filed a patent in December 1947 but the field did not really advance until the development of the laser in 1960.

The first holograms that recorded 3D objects were made by Yuri Denisyuk in the Soviet Union in 1962;later by Emmett Leith and Juris Upatnieks in University of Michigan, USA in 1962. Advances in photochemical processing techniques, to produce high-quality display holograms were achieved by Nicholas J. Phillips. Several types of holograms can be made. Transmission holograms, such as those produced by Leith and Upatnieks, are viewed by shining laser light through them and looking at the reconstructed image from the side of the hologram opposite the source. A later refinement, the "rainbow transmission" hologram allows more convenient illumination by white light rather than by lasers or other monochromatic sources.

Rainbow holograms are commonly seen today on credit cards as a security feature and on product packaging. These versions of the rainbow transmission hologram are commonly formed as surface relief patterns in a plastic film, and they incorporate a reflective aluminium coating which provides the light from "behind" to reconstruct their imagery. Another kind of common hologram, the reflection or Denisyuk hologram is capable of multicolour image reproduction using a white light illumination source on the same side of the hologram as the viewer. A diffraction grating is a structure with a repeating pattern. A simple example is a metal plate with slits cut at regular intervals. Light rays travelling through it are bent at an angle determined by λ, the wavelength of the light and d, the distance between the slits and is given by sinθ = λ/d.

Holography is "lensless photography" in which an image is captured not as an image focused on film, but as an interference pattern at the film. Typically, coherent light from a laser is reflected from an object and combined at the film with light from a reference beam. This recorded interference pattern actually contains much more information that a focused image, and enables the viewer to view a true three-dimensional image which exhibits parallax. That is, the image will change its appearance if you look at it from a different angle, just as if you were looking at a real 3D object. In the case of a transmission hologram, you look through the film and see the three dimensional image suspended in midair at a point which corresponds to the position of the real object which was photographed.

In 1972 Lloyd Cross developed the integral hologram by combining white-light transmission holography with conventional cinematography to produce moving 3-dimensional images. Sequential frames of 2-D motion-picture footage of a rotating subject are recorded on holographic film. When viewed, the composite images are synthesized by the human brain as a 3-D image. In 70's Victor Komar and his colleagues at the All-Union Cinema and Photographic Research Institute (NIFKI) in Russia, developed a prototype for a projected holographic movie. Images were recorded with a pulsed holographic camera. The developed film was projected onto a holographic screen that focused the dimensional image out to several points in the audience.

A one-meter square hologram of an architectural model shows how an architect can realize a space in three dimensions before a project is built. A holographic image of the Lindow Man , the 2000-year-old remains of a man discovered in a bog in England, demonstrates the use of holography for anthropological, educational, and archival purposes. Also featured are works by MIT Professor Stephen Benton (1941-2003), inventor of the white light-viewable hologram. The holographic imaging process uses laser light to store and reproduce three-dimensional images. Invented in the late 1940s, holography is best known for industrial and commercial applications ranging from credit card security to product packaging. Many artists have experimented with holography's creative properties since the late 1960s.