In the entire ecosystem of the Earth, all kinds of living creatures get the energy in their unique ways for survival, growth and reproduction. The Sun is by far the most important source of energy for all the animals and plants on Earth. The Sun warms the Earth, drives the water cycle and sustains life on Earth. The plants as food producers, absorb the Sun's energy and convert the energy into food for themselves and others. Some dead animals and plants, buried deeply underground, were gradually converted into coal, oil and other resources for human use -- all these are also the energy from the Sun.