Photosynthesis is the process by which plants make their own food. During photosynthesis, plants use sunlight, usually captured by their leaves, to convert carbon dioxide from the air and water from the soil into glucose, a type of sugar that serves as food. This process also produces oxygen as a byproduct, which is essential for the survival of most living organisms on Earth. Photosynthesis occurs primarily in the chloroplasts of plant cells, where chlorophyll (the green pigment) absorbs light energy. This process is fundamental for life on Earth, as it forms the basis of most food chains.