What is the name of the process by which plants convert light into chemical energy?

The process by which plants convert light into chemical energy is photosynthesis.

In plant cells, chlorophyll and other pigments absorb light inside chloroplasts. The light-dependent reactions use that energy to produce ATP and NADPH, which power the Calvin cycle. The cycle captures carbon dioxide and helps build sugars, storing energy in chemical bonds.

Oxygenic photosynthesis uses water as an electron source and releases oxygen as a byproduct. A simplified overall equation is 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂, although real photosynthesis involves many intermediate reactions. Plants use the resulting sugars to make starch, cellulose, lipids and other compounds.

A common mix-up is confusing photosynthesis with cellular respiration. Photosynthesis stores energy in organic molecules, while respiration breaks those molecules down to release usable energy. Jan Ingenhousz demonstrated in 1779 that light is essential to the process.