Composite volcanoes, also known as stratovolcanoes, are tall, steep-sided mountains formed by alternating layers of lava flows, ash, and volcanic rocks. They typically erupt explosively due to the thick, viscous nature of their magma, which can trap gas. This results in powerful eruptions that can produce pyroclastic flows and ash clouds. These volcanoes are commonly found at convergent plate boundaries, where an oceanic plate subducts beneath a continental plate. Famous examples of composite volcanoes include Mount St. Helens in the United States and Mount Fuji in Japan. Their eruptions can significantly impact the surrounding environment and human activities.