I'm trying to understand carbon processing in plants and am using Thornley & France¹ as a reference. They have a very detailed account of photosynthesis which begins with this overview statement (p. 289):

Overall, photoshythesis can be summarized by:

       light

CO₂ + H₂O -> {CH₂O} + O₂

This reaction indicates that light energy is used to convert substrates, CO₂ and H₂O into a higher energy state, in which CO₂ is reduced to carbohydrate and at the same time H₂O is oxidized to molecular oxygen, O₂. {CH₂O} indicates carbohydrate; in fact, glucose (C₆H₁₂O₆) is produced, which contains six {CH₂O} units.

Oxygen is excreted as a byproduct of the photosynthetic reaction.

¹ Thornley, J.H.M, France, J. (2006) Mathematical Models in Agriculture. 2nd Edition. C A B Intl. Cambridge, MA.