A photochromic material is an object or substance that is capable of reversibly changing in color or shade from light exposure. This reversible process includes brightening or darkening from a high sufficient frequency of light such as ultraviolet radiation. In the absence of activating light, photochromic materials could return to their original state of color. Fabrics, fibers, glass, plastic, and powder are some examples that could be photochromic with changes in light intensity.