The document describes the rock cycle, which is the continuous process by which the three main types of rocks are formed from one another through various processes. Igneous rocks form from the cooling and crystallization of magma or lava. Sedimentary rocks form through the compaction and cementation of sediments. Metamorphic rocks form through heat and pressure acting on existing rocks. The rock cycle is powered by Earth's internal heat and the energy from the sun, and it connects geological surface processes like weathering and erosion to interior processes like melting and recrystallization.