This document discusses the three main types of rocks: igneous, sedimentary, and metamorphic rocks. It provides details on how each type forms and key characteristics. Igneous rocks form from the cooling and solidification of magma or lava. Sedimentary rocks form through the compaction and cementation of sediments like sand and shells. Metamorphic rocks form from the alteration of existing rocks like igneous or sedimentary rocks through heat, pressure, and chemical changes. Rocks are classified based on their formation process and texture.