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, located in chloroplasts, absorbs sunlight and uses its energy to convert carbon dioxide and water into oxygen and energy-rich glucose. This process occurs through two stages - the light-dependent reactions where ATP and NADPH are produced, and the Calvin cycle where glucose is assembled. Photosynthesis provides the foundation for life on Earth by producing oxygen and glucose, the primary energy source for most organisms.