Photosynthesis is the process in which a plant uses radiant energy from the sun to turn carbon dioxide and water into oxygen and glucose (energy) and water.
It is a process that is responsible, in many ways, for life on earth. Plants use this process to reduce the amount of carbon dioxide that is generated and produce oxygen, which is necessary for aerobic life forms (like human beings) to survive. The process also generates glucose, which is converted over to energy and in turn, more biomass. This resultant biomass serves as food for other life forms. Thus, we can attribute breathable air and food to plants, which in turn is generated by photosynthesis. Green plants contain chlorophyll that enables the photosynthetic activity.
6CO2 + 12H2O + sunlight --> C6H12O6 + 6O2 + 6H2O.