Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy, usually from the sun, into chemical energy in the form of glucose. This process involves two main stages: the light-dependent reactions and the light-independent reactions (Calvin Cycle). In the light-dependent reactions, which take place in the thylakoid membrane, light energy is converted to chemical energy (ATP and NADPH). This chemical energy is then used in the Calvin Cycle to convert carbon dioxide into glucose.