Igneous rock is the type of rock formed from the cooling and solidification of magma or lava. This process can occur either beneath the earth’s surface, producing intrusive igneous rocks like granite, or on the surface during volcanic eruptions, resulting in extrusive igneous rocks like basalt. The mineral composition, cooling rate, and original magma source determine the characteristics of the resultant rock. Igneous rocks form the foundational layer of the Earth’s crust and play a critical role in the rock cycle, influencing landscape and geological structures.