The sun provides all of the external energy given to Earth. It provides energy and food for the plants and algae that form the base of the food chain. Without the sun's external energy, the bottom level of the food pyramid would be entirely gone, and there would be no support for the upper levels including plant eaters, and also carnivores. Some microbial life does exist deep in the oceans outside this chain that does not require the sun's energy. Instead, these organisms get energy from heat around volcanic vents very deep in the ocean.

The sun gives us energy. The sun heats the Earth, keeping the Earth from freezing into a ball of ice. The sun's light also gives the energy for plants, which then provide the food we eat.