The melted rock that forms a volcano is called

The melted rock that forms a volcano is called magma.

Magma is present beneath the earth's surface and when the magma is cooled to form a solid than it is known as igneous rock, we consider the lava as a type of this so we can say that when magma reaches the surface of earth than it becomes lava. The reason behind the occurrence of v olcanoes is the movement of plates of earth.