The document discusses geothermal energy. It defines geothermal energy as heat from within the earth, coming from the Greek words "geo" meaning earth and "therme" meaning heat. It also explains that geothermal fields are found at tectonic plates where there are more volcanoes, and these areas are suitable for geothermal power plants. Finally, it provides a diagram labeling the layers of the earth and briefly describes the process of how geothermal energy is used to generate electricity.