Photosynthesis is the process through which plants, algae and some bacteria use the sun’s energy to create organic matter. Photosynthetic life forms use the light energy to transform carbon dioxide and water into sugar (organic matter) and oxygen. That is why plants and algae are very important for the Earth’s biosphere, because they regulate the atmosphere’s content in oxygen.
The photosynthetic organisms have played a crucial role in the development of life on Earth, as they changed the composition of the atmosphere, and thus enabled life to thrive also on land and not only in the oceans.
Equation of the overall process of photosynthesis. Courtesy of Wikipedia.