1. Volcanic (Extrusive) Igneous Rock:
This is the type of igneous rock formed as a result of pressure which forces the molten magma to the earth surface. Volcanic igneous rocks cools and solidifies on the earth surface.
2. Plutonic (intrusive) Igneous Rock:
This is the type of Igneous rock that is formed with the earth crust due to low pressure that is not enough to force it to the surface of the earth. The plutonic igneous rock cools and solidifies gradually beneath the earth surface: