A volcano is a mountain that forms when magma reaches the surface of the Earth. Magma rises because it is less dense than the solid rock around it. This lecture briefly describe on what are the parts of a Volcano. VENT- the vent is the opening from which lava flows. Crater- the top of the volcano. Volcanic cone- is the pile of lava, dust, ashes, and rock around the vent. There are three types of Volcanoes: Shield, Cinder Cone and Composite.