What gas do plants absorb from the air for photosynthesis?

Plants are basically factories that turn carbon dioxide, water, and sunlight into both glucose (their favorite snack) and oxygen (our crucial snack). The process was first discovered in 1779 by Jan Ingenhousz, who probably got some weird looks while putting plants underwater to watch them release tiny oxygen bubbles in the sunlight. The discovery helped explain why plants are crucial for maintaining Earth's breathable atmosphere.