Chloroplasts are organelles found in plant cells and some types of algae. They are responsible for the process of photosynthesis, which is the conversion of light energy into chemical energy in the form of glucose (a type of sugar). During photosynthesis, chloroplasts use chlorophyll, a green pigment, to capture light energy and convert carbon dioxide and water into glucose and oxygen. This process is vital for the production of food and oxygen in the plant and plays a critical role in the Earth's ecosystem by providing energy for many organisms.