A geyser is a natural hot spring that intermittently erupts, sending a column of hot water and steam into the air. This phenomenon occurs when underground water is heated by geothermal energy, often from magma beneath the Earth's surface. When pressure builds up, the water is forced out through a vent, creating a spectacular display. Geysers are commonly found in areas with volcanic activity, such as the Yellowstone National Park in the United States. The most famous geyser in this park is Old Faithful, known for its regular eruptions. Geysers are important for studying geothermal energy and understanding Earth's geological processes.