Interference in photography and optics refers to the phenomenon that occurs when two or more light waves meet and either reinforce or cancel each other. This interaction of waves can produce patterns of light and dark, or create colourful effects, depending on how the waves overlap.
Interference is the principle behind holography, thin-film effects, and some types of diffraction patterns. Understanding interference is useful for photographers and optical engineers when working with special effects, coatings, or holographic imaging, helping them predict and control how light interacts to produce unique visual results.