Here's why:

* Igneous rocks form from the cooling and solidification of molten rock.

* Magma is molten rock found beneath the Earth's surface.

* Lava is magma that has erupted onto the Earth's surface.

* Extrusive rocks are formed when lava cools and solidifies quickly, often resulting in fine-grained textures. Examples include basalt, rhyolite, and obsidian.

Intrusive igneous rocks, on the other hand, are formed when magma cools and solidifies slowly beneath the Earth's surface, resulting in larger crystals.