Here's a breakdown:

* Lava: Molten rock that erupts from a volcano.

* Cooling: As lava cools, it solidifies.

* Igneous rocks: Rocks formed from the cooling and solidification of magma or lava.

The specific type of igneous rock formed depends on the composition of the lava and how quickly it cools.

Here are some examples:

* Extrusive igneous rocks: Formed from lava that cools quickly on the Earth's surface. These rocks tend to be fine-grained because the crystals have less time to grow. Examples include basalt, rhyolite, and obsidian.

* Intrusive igneous rocks: Formed from magma that cools slowly beneath the Earth's surface. These rocks tend to be coarse-grained because the crystals have more time to grow. Examples include granite and gabbro.

So, the answer to your question is igneous rocks.