The document provides information about rock formation and classification. It defines igneous, sedimentary and metamorphic rocks. Igneous rocks form from cooling magma, either below the surface (intrusive) or above (extrusive). Sedimentary rocks form through compaction and cementation of sediments. Metamorphic rocks form from changes to existing rocks through heat, pressure and fluids. Rocks are classified based on texture, composition and formation processes. The rock cycle illustrates how rocks continuously change between the three main types through various natural processes.