Holograms have a myriad of applications, the key ones - and those most relevant to the membership of IHMA - being authentication and brand enhancement.
Holograms are part of a family of technologies known as diffractive optically variable devices (DOVIDs). They exhibit a variety of complex images and patterns according to the viewing angle (eg if they are tilted, rotated), based on the diffraction of light. Hence the collective name DOVID, although they are more commonly known as holograms.
In reality, this is a misnomer, as holograms are a type of DOVID, but not all DOVIDs are holograms. Holograms (the word comes for the Greek meaning "whole image") are created through the interference of two laser beams, but there are now other ways through the use of diffraction to create similar-looking images, including electron (e) beam etching, laser etching and other techniques.
Many companies have developed proprietary types of DOVID for which there are proprietary designations or brand names, but very few people outside of the industry can tell the difference between these and holograms. So while 'hologram' strictly speaking refers to one type of DOVID it has come to be used almost as a synonym, taken to refer to all kinds of reflective, kinetic or 3D image device.
For ease of reference, we are using the term here even though it (and indeed the activities of some of the members of the IHMA) also encompasses other forms of DOVID.