Geothermal energy is the energy stored within the earth. Inside the earth, molten rocks constitute the Magma. The magma sometimes erupts to form volcanoes on the surface of the earth. This magma heats up pools of water within the earth and hence these hot water reservoirs (geothermal reservoirs) are formed.

With the use of modern technology, wells are drilled to harness water from these reservoirs. Hot water gushes out and is used to generate heat energy, electricity and industrial use.