The overall chemical reaction involved in photosynthesis is:
6CO₂ + 6H₂O (+ light energy) → C₆H₁₂O₆ + 6O₂.
This is the source of the O2 we breathe, and thus, a significant factor in the concerns about deforestation.
There are two parts to photosynthesis. They are called the light reaction and the dark reaction