Photosynthesis is the process by which green plants make their own food using carbon dioxide from the air and water from the soil in the presence of sunlight. Chlorophyll, the green pigment in leaves, captures solar energy. The raw materials are carbon dioxide and water. Sunlight provides the energy, and chlorophyll acts as the catalyst. The main products formed are glucose (food for the plant) and oxygen, which is released into the atmosphere. This vital process sustains almost all life on Earth.