Energy is the stuff we need to accomplish physical actions such as walking, lifting a glass, heating some water, or powering a television set.
energy is a property of objects which can be transferred to other objects or converted into different forms, but cannot be created or destroyed.
Energy is the capacity of a system to do work. That system may be a jet, carrying hundreds of passengers across the ocean. A baby’s body, growing bone cells. A kite, rising on the wind. Or a wave of light crossing a space.