There are three main types of rocks: igneous, sedimentary, and metamorphic. Igneous rocks form from cooled molten rock, either from lava on the surface or magma beneath the earth. Common examples include granite and basalt. These rocks can be found in many landscapes, often creating mountains and volcanic formations. Sedimentary rocks are made from particles and organic materials that have settled over time, often in water. They can contain fossils and are usually layered, like sandstone and limestone. Metamorphic rocks start as either igneous or sedimentary rocks but change due to heat and pressure, resulting in rocks like marble and schist.