ELI5: How do plants make their own food?

Plants make their own food by using sunlight, air, and water in a magical cooking process called photosynthesis.

Think of a plant's green leaves as tiny home kitchens. Just like you need ingredients and an oven to bake cookies, a plant needs three simple everyday ingredients to make its meals:

• Sunlight (The Oven): The plant’s leaves catch sunshine like solar panels. Inside the leaves is a special green helper called chlorophyll, which absorbs the sunlight to power the cooking.
• Water (The Liquid): When it rains or when you water a potted houseplant, the roots deep in the soil act like drinking straws, sucking up moisture and sending it up the stem to the leaves.
• Carbon Dioxide (The Secret Spice): Leaves have microscopic mouths on their undersides called stomata. They use these tiny openings to breathe in an invisible gas from the air called carbon dioxide, which is the same gas that humans breathe out.

This glucose is pure plant food. The plant eats it to grow taller, sprout colorful flowers, and make tasty fruits for us to eat.

The best part of this plant cooking is the leftovers. When the plant is done baking its sweet food, it produces oxygen, which it breathes back out into the air. That means every time a plant cooks its lunch, it cleans the air and makes the fresh oxygen that you and I need to breathe every single day.