Answer: Igneous rock is formed by the melting and cooling of magma or lava.
Inside of Earth, magma slowly cools, creating rock with an irregular or rough texture and large crystals. Magma cooling inside Earth creates intrusive igneous rock.
Outside of Earth, lava cools very quickly, creating rock with a fine, grainy look or texture and small crystals. Lava cooling outside of Earth creates extrusive igneous rock.
Examples: granite, basalt, and pumice