Here's a breakdown:

* Magma: Molten rock found beneath the Earth's surface.

* Eruption: When magma reaches the surface, it's called lava.

* Cooling: As lava cools and solidifies, it forms extrusive igneous rocks.

The rapid cooling of lava leads to the formation of fine-grained or glassy textures, as the crystals don't have time to grow large. Examples of extrusive igneous rocks include:

* Basalt: A dark-colored, fine-grained rock often found in volcanic flows.

* Rhyolite: A light-colored, glassy rock formed from felsic lava.

* Obsidian: A black, glassy rock that cools very quickly.

* Pumice: A light, porous rock formed from frothy lava.

Let me know if you'd like to learn more about any specific type of extrusive igneous rock!