Cells must create energy in order to survive, and all life is made up of cells. Almost everything cells, animals and plants do requires energy. It is required for metabolism, movement and breathing. In many ways, life can be conceptualized as a form of energy manipulation.
Movement also depends on energy. All forms of transportation, from walking to flying in an airplane, require converting energy into movement. Because of this, energy is a core part of civilization. Without transportation, trade is impossible.
Electricity is perhaps the most versatile type of energy. It can be converted to movement and to create heat, and it is essential for powering the computers modern society depends on. Coal, oil and other fossil fuels are the result of plants and animals dying and leaving behind energy-rich matter. This matter can be converted into electricity or mechanical energy. Solar and wind power use the energy provided by the sun to create electrical energy; nuclear energy exploits atomic forces to create a tremendous amount of energy while using little matter.