Geysers are natural hot springs that periodically erupt with water and steam. They occur in areas with volcanic activity, where underground water is heated by magma. When the pressure builds up, the water is forced to the surface, creating a spectacular display. The most famous geyser is Old Faithful in Yellowstone National Park, which erupts approximately every 90 minutes. Geysers are part of a larger geothermal system, which includes hot springs and fumaroles. They provide valuable insights into the Earth's geothermal activity and are popular attractions for tourists and scientists alike.