Invented in the 1940’s but not created until the 1960’s (when laser beams were developed) holograms are an advanced form of photography that allows an image to be recorded in 3 Dimensions.
Holograms are created by firing a laser beam at an object via a beam splitter, mirrors and a lens to create “interference”. The split beams (‘object’ & ‘reference’) collect the information on the objects shape & dimensions then record this on a holographic plate behind.
Holograms that change appearance as you move around them (i.e the clowns, lizards & statue holograms) are just several holographic exposures stitched together and is called a Volumetric Display
Holography is used in many applications from product testing, medicine and security to consumer packaging and in data storage. They say that entire contents of the US library of Congress (20 million books) can be stored in a hologram the size of a sugar cube!