Here's a breakdown of what happens:

* Photosynthesis: Plants use sunlight, water (H2O), and carbon dioxide (CO2) to produce glucose (sugar) and oxygen.

* The Reaction: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2

* Waste Product: Oxygen is a byproduct of this reaction and is released into the atmosphere as a waste product.

This oxygen is essential for the survival of many organisms, including humans, who use it for respiration.