The sun gives everything all of its energy. This is the starting point of the food chain.

This is all trees, grasses, and bushes. Basically all plants. Usually the primary consumer eats the primary producer.

The primary consumer are animals who eat the primary producer. They are usually eaten by the rest of the consumers.

The secondary consumer eats the primary consumer, and sometimes the primary producer.

The tertiary consumer eats the secondary consumer, primary consumer, and sometimes the primary producer.

The quaternary consumer eats the tertiary, secondary, primary consumers, and sometimes the primary producer.

This is the last link in the food chain. It decomposes, or breaks down, the dead plants and animals.