Photosynthesis is of vital importance to the continuation of life on earth. Here are reasons for its importance:

- Production of oxygen: Photosynthesis is the reverse of respiration. This is why the supply of atmospheric oxygen is not exhausted by respiration and combustion. The forests of the world contribute more than 60% of the world’s oxygen demands. They also absorb the massive doses of carbon dioxide exhaled into the atmosphere by modern industrial societies.

- Food production: Plants manufacture all their body-building and energy-producing substances from simple raw materials using the energy of the sunlight. Animals obtain their food from plants.

- Energy: Fossil fuels such as coal are formed from plants and as such the energy stored in them comes from photosynthesis.