What is photosynthesis?

Photosynthesis is the process by which green plants, algae, and certain bacteria capture light energy and convert it into chemical energy. Using the pigment chlorophyll, they absorb sunlight and combine carbon dioxide from the air with water from the soil to produce glucose (a sugar that stores energy) and release oxygen as a byproduct. This single process is the foundation of nearly every food chain and is responsible for the oxygen-rich atmosphere we breathe. Globally, photosynthesis captures roughly 100–115 billion tonnes of carbon each year, and phytoplankton in the oceans produce an estimated half of the planet’s oxygen.