Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, water and carbon dioxide to produce oxygen and energy in the form of glucose. Chlorophyll, a green pigment found in leaves, stems and chloroplasts, is essential in photosynthesis as it absorbs energy from sunlight. The overall reaction is: 6CO2 + 6H2O + Light energy → C6H12O6 + 6O2. Photosynthesis occurs in two stages: the light-dependent reactions and the light-independent reactions.