A hologram is a physical structure that diffracts light into an image. It is a photographic recording of a light field, rather than an image formed by a lens. Holography is a technique that enables a wavefront to be recorded and later reconstructed. Holograms can be created by superimposing a second wavefront on the wavefront of interest, generating an interference pattern which is recorded on a physical medium. When only the second wavefront illuminates the interference pattern, it is diffracted to recreate the original wavefront. Holograms can also be computer-generated by modelling the two wavefronts and combining them digitally. A hologram can reproduce a 3D light field using diffraction, and the reproduced light field can generate an image which still has the depth, parallax, and other properties of the original scene. Holograms can be seen by looking into an illuminated holographic print or by shining a laser through a hologram and projecting the image onto a screen. Holograms can be used to present complex technical concepts as well as showcasing visually appealing products.