Here's a breakdown:

* Sunlight contains photons, which are tiny packets of energy.

* Chlorophyll, a green pigment found in plants, absorbs these photons.

* The absorbed energy is used to split water molecules, releasing electrons and protons.

* These electrons are then used to power the synthesis of ATP (adenosine triphosphate), the main energy currency of cells.

* The ATP is then used to convert carbon dioxide into glucose, the sugar that plants use for energy and growth.

So, in short, sunlight is the primary source of energy for photosynthesis. The energy from sunlight is captured by chlorophyll and used to fuel the process of turning carbon dioxide and water into sugar and oxygen.