Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Photoinhibition is light-induced reduction in the photosynthetic capacity of a plant, alga or a cyanobacterium. Photosystem II (PSII) is more sensitive to light than the rest of the photosynthetic machinery, and most researchers define the term as light-induced damage to Photosystem II. In living organisms, photoinhibited PSII centres are continuously repaired via degradation and synthesis of the D1 protein of the photosynthetic reaction center of PSII. Photoinhibition has also been used in a wider sense, (see dynamic photoinhibition below). Several recent reviews on photoinhibition are available.