Which process is responsible for the formation of igneous rocks?

The formation of igneous rocks is primarily due to the cooling and solidification of magma or lava. When molten rock material, known as magma, rises to the Earth's surface and cools, it solidifies to form igneous rocks. If this cooling occurs beneath the Earth's surface, the resulting rocks are classified as intrusive (or plutonic) igneous rocks, such as granite. In contrast, if the magma erupts onto the surface as lava and cools quickly, it forms extrusive (or volcanic) igneous rocks, like basalt. The process involves a significant temperature drop, allowing the minerals in the magma to crystallize and bond together, creating the crystalline structure characteristic of igneous rocks. Understanding this process is fundamental in geology, as it explains how the Earth recycles its materials and shapes its crust.