Specifically, it's the light energy from the sun that is captured by chlorophyll, a green pigment found in plants and other photosynthetic organisms. This light energy is then used to convert carbon dioxide and water into glucose (sugar) and oxygen.

Here's a simple breakdown:

* Light energy + Carbon dioxide + Water --> Glucose + Oxygen

So, while the process of photosynthesis involves chemical reactions and the conversion of matter, it all starts with the light energy from the sun.