A passage followed by magma inside a volcano or underground is called a conduit. Magma typically consists of molten or partially molten rock, and it may contain crystallized minerals, xenoliths from the conduit, a liquid portion or melt, and dissolved gases. Once magma reaches the surface, it is considered lava.
Another part of a volcano is the magma chamber, which stores a large amount of molten rock under pressure beneath the Earth's crust. The main vent is a point on the Earth's crust that is weakened and allows magma to reach the surface. The top part of the main vent is considered the throat, which is the place where ash, rock and lava erupt from the volcano. Some volcanoes contain secondary vents, which allow lava to erupt from multiple points.