There are three types of volcanoes: active volcanoes that have erupted recently and may erupt again, dormant volcanoes that are currently inactive but could erupt in the future, and extinct volcanoes that will not erupt again. Examples of active volcanoes discussed are Kilauea in Hawaii, the most active volcano in the world, and Arenal in Costa Rica. Mount Fuji in Japan is currently dormant. Anatahan was thought to be extinct but erupted in 2003. Vesuvius in Italy is extinct but had a devastating eruption in the past that buried the city of Pompeii under ash.