The type of rock formed through volcanic activity is called igneous rock. It forms from the cooling and solidification of molten rock material, known as magma or lava. If the cooling occurs underground, the resulting igneous rock is called intrusive (or plutonic), while if it cools on the surface after a volcanic eruption, it is termed extrusive (or volcanic). Common examples include granite (intrusive) and basalt (extrusive), both of which are integral to the Earth's crust and geological processes.