* Producers (autotrophs): Plants, algae, and some bacteria are able to directly harness the sun's energy through photosynthesis. They convert light energy into chemical energy stored in the bonds of glucose (a sugar). This is the foundation of the food chain.

* Consumers (heterotrophs): Animals, fungi, and most bacteria cannot directly use sunlight. They get their energy by consuming producers or other consumers that have eaten producers. This means they are indirectly getting their energy from the sun.

In short, the sun is the primary energy source for almost all life on Earth.