Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy, usually from the sun, into chemical energy stored in glucose. This occurs primarily in the chloroplasts of plant cells, where chlorophyll captures light energy. During photosynthesis, carbon dioxide and water are used to produce glucose and oxygen as byproducts. This process is essential for life on Earth, as it provides the oxygen we breathe and forms the basis of the food chain.