The process plants use to convert sunlight into energy is called photosynthesis. During this process, chlorophyll in plant cells absorbs sunlight and utilizes its energy to convert carbon dioxide from the air and water from the soil into glucose, which serves as food for the plant. Oxygen is produced as a byproduct and released into the atmosphere. Photosynthesis is crucial for life on Earth, as it not only provides energy for plants but also supports the food chain and contributes to the oxygen content of the atmosphere.