Need for energy:

            Energy is a fundamental concept in science. It links almost all the natural phenomena. When we say that a body has energy, we mean that it can do work, so it possesses energy. The energy from running water can be used to run the water mills or water turbines.

              Energy exists in various forms such as mechanical energy, heat energy, light energy, sound energy, electrical energy, chemical energy, nuclear energy, etc. Energy can be transformed from one form into another.