A mountain with a center of hot magma is called a volcano. Under the right circumstances, volcanoes erupt and release a flow of lava. When this happens, they are as beautiful as they are scary and dangerous. Although most people recognize images of erupting volcanoes, they may not know a lot about them. Fortunately, there are a lot of interesting facts that can help you understand volcanoes, what makes them erupt, and what happens when they do. Includes a list of links for more information.