Extrusive igneous rocks are formed when molten rock, or magma, erupts onto the Earth's surface through volcanic activity. Once exposed to the cooler temperatures of the atmosphere or ocean, this magma solidifies quickly, resulting in fine-grained textures. Common examples of extrusive igneous rocks include basalt and pumice. These rocks are typically found in areas with volcanic activity, such as mid-ocean ridges and volcanic islands. The rapid cooling process prevents large crystals from forming, making extrusive igneous rocks distinct from their intrusive counterparts, which cool slowly beneath the surface.