Photosynthesis is a food making process in green plants. In this process, plants use energy from light to produce food. Photosynthesis also provides oxygen for all living organisms. Photosynthesis is the chief function of plant leaves. The process begins when light strikes the leaf’s chloroplasts. Chloroplasts are small green bodies found in the plant's cells. They can occur in the slender cells of the plants, palisade tissue or in the broad, irregularly shaped cells of the spongy tissue. Energy from the light is absorbed by chlorophyll, which is the green pigment or colouring matter in the chloroplasts. Partly surrounding each cell of the palisade and spongy tissues is an air space filled with carbon dioxide, water vapor, and other gases. The energy absorbed by the chlorophyll splits the water molecules in these spaces into molecules of hydrogen and oxygen. The hydrogen then combines with carbon dioxide to produce a simple sugar. The excess oxygen enters the air through the stomata, or pores, of the leaf. People, animals and all other living organisms need oxygen in order to live. The sugar produced by photosynthesis is carried throughout the plant in special tube-like cells. These cells make up the plants, flow them or food transporting tissue. The sugar can be burned in order to release energy for the plant's growth, or it can be combined with various minerals. These minerals enter the plant through the roots. The combination of sugar and minerals produces vital compounds such as proteins and vitamins. These compounds provide nourishment for the plan. The energy and nourishment created by photosynthesis provide all the food that people, and other animals eat. Animals either eat plants directly or eat animals that eat the plants.