There are three main types of rocks: igneous, sedimentary, and metamorphic. Igneous rocks form from the cooling and solidification of molten material called magma or lava. Examples include granite and basalt. Sedimentary rocks are created from the accumulation of mineral and organic particles, often in layers. Common examples are sandstone and limestone. Metamorphic rocks arise when existing rocks undergo changes due to heat, pressure, or chemical processes. Notable examples include schist and marble. Each type of rock plays a vital role in the Earth's geology.