Photosynthesis is when plants and potentially other organisms use the sun’s light to create food for themselves out of water and carbon dioxide (CO2). Oxygen is a byproduct of this.
Here’s an official definition from Oxford dictionary as well:
“the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a byproduct.”
Hope this helps!
