There are three main types of photosynthesis: C3, C4, and CAM. C3 photosynthesis is most efficient under normal conditions and is used by most plants. C4 photosynthesis is faster under high heat/light and avoids photorespiration. C4 plants include many grasses and desert plants. CAM photosynthesis stores CO2 at night and is most efficient for water use; it is used by plants like cacti and bromeliads.