What is the name of the process by which plants convert sunlight into energy?

The process by which plants convert sunlight into energy is photosynthesis.

Photosynthesis converts light energy into chemical energy. In most plants, it takes place mainly in chloroplasts, where the green pigment chlorophyll absorbs light. Using carbon dioxide from the air and water taken up by the roots, the plant builds energy-rich carbohydrates, including sugars, while oxygen is released as a by-product.

The process is more precise than the shorthand idea that plants simply “turn sunlight into food.” Sunlight supplies the energy, but carbon dioxide provides carbon atoms and water contributes hydrogen and oxygen. The sugars made through photosynthesis support growth, respiration, storage, and the construction of materials such as cellulose.

Photosynthesis also occurs in algae and cyanobacteria, not just land plants. It is different from respiration: photosynthesis stores energy in organic molecules, while cellular respiration breaks those molecules down to make usable energy for cells. Light intensity, temperature, water availability, leaf area, and carbon-dioxide supply can all affect its rate.