In photography, sensitive material refers to any substance that reacts to the actinic (or light-sensitive) power of light. This includes photographic films, plates, and papers coated with light-sensitive compounds such as silver halides, which undergo chemical changes when exposed to light to capture an image.
Understanding sensitive materials is fundamental to photography, as the type and sensitivity of the material directly affect exposure, image quality, and the choice of processing techniques. Photographers select materials based on their light sensitivity, tonal range, and intended creative outcome to achieve the desired results in both film and alternative photographic processes.