ABSTRACT
Photochromism is an exemplary field of photochemistry that deals with photochemical reactions that are reversibly thermally or photoinduced. This term is made up of two parts — photo (light) and chroma (color) — and the suffix “ism“ indicates the phenomenon. Photochromism literally means coloration by light. It has received considerable attention ever since its discovery toward the end of the 19th century, both for organic or inorganic substances, and is still an active field of research, primarily because of its actual and potential applications and for its paramount importance in biological phenomena.
