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Igneous rocks are one of the three main rock types, alongside sedimentary and metamorphic rocks. They are formed through the cooling and solidification of molten rock material, which can originate from beneath the Earth's surface as magma or erupt onto the surface as lava. The composition and texture of igneous rocks are determined by the conditions under which they cool and solidify.

There are two primary classifications of igneous rocks based on their formation location. Intrusive igneous rocks, also known as plutonic rocks, form when magma cools and solidifies slowly beneath the Earth's surface. This slow cooling allows for the formation of larger mineral crystals, giving these rocks a coarse-grained texture. Examples include granite and gabbro.

Extrusive igneous rocks, also called volcanic rocks, form when lava cools and solidifies rapidly on the Earth's surface. The rapid cooling results in smaller mineral crystals, creating a fine-grained or even glassy texture. Examples include basalt, obsidian, and pumice. Igneous rocks are abundant and form the bedrock of many continents and the ocean floor. Their study provides valuable insights into the Earth's geological history and internal processes.