In physics and photography, a quantum is the smallest indivisible unit of radiant energy, commonly associated with light. Each quantum of light is also called a photon, and it carries a discrete amount of energy determined by its wavelength.
Understanding quanta is essential in digital imaging, low-light photography, and sensor technology, as it explains how light interacts with film emulsions, CCDs, and CMOS sensors. The concept underpins the principles of exposure, sensitivity, and photon-based image capture, making it a fundamental term in both scientific and photographic contexts.