Active volcanoes are geological formations that are currently erupting or have erupted in recent history. They can release lava, ash, and gases into the atmosphere, which can impact the surrounding environment and communities. The activity of these volcanoes is monitored by scientists to predict potential eruptions and ensure public safety. There are different types of active volcanoes, including shield volcanoes, stratovolcanoes, and cinder cone volcanoes. Each type has distinct characteristics and eruption styles. Famous active volcanoes include Mount St. Helens in the United States and Kilauea in Hawaii, both of which have had significant eruptions in the past.