Here's why:

* Photosynthesis: Chloroplasts are the sites of photosynthesis. This process uses sunlight, water, and carbon dioxide to create glucose (sugar) as food for the plant.

* Chlorophyll: Chloroplasts contain chlorophyll, a green pigment that absorbs sunlight energy.

* Structure: Chloroplasts are enclosed by a double membrane and contain stacks of internal membranes called thylakoids, where light-dependent reactions of photosynthesis occur.

Let me know if you'd like to learn more about chloroplasts or photosynthesis!