Modern civilization is possible because people have learned how to change energy from one form to another and then use it to do work. People use energy to walk and bicycle, to move cars along roads and boats through water, to cook food on stoves, to make ice in freezers, to light out homes and offices, to manufacture products, and to send astronauts into space. There are many different forms of energy, including heat, light, motion, electrical, chemical, and gravitational.
