Almost all the energy used by living things comes from the sun.

Here's how it works:

* Photosynthesis: Plants and other photosynthetic organisms capture sunlight and use it to convert carbon dioxide and water into sugars (like glucose). This process stores energy from the sun in the chemical bonds of the sugars.

* Food Chain: Animals eat plants, obtaining the energy stored in those sugars. This energy is then passed up through the food chain as animals eat other animals.

In essence, the sun provides the primary source of energy for almost all life on Earth.