This document discusses different forms of energy including kinetic, potential, mechanical, chemical, sound, thermal, electrical, gravitational, radiant, magnetic, nuclear, elastic, light, solar, wind, and hydroelectric energy. It also covers renewable energy sources like solar, wind, and hydroelectric versus non-renewable sources like fossil fuels. Examples are given of different machines that convert these energy forms like steam engines, internal combustion engines, steam turbines, and gas engines. The environmental impacts of generating, transmitting, distributing, and using energy are also summarized.