The rock cycle is all a part of the dynamic Earth that we live on. It demonstrates how the 3 major rock types are all intertwined with one another. These 3 are: Igneous, Metamorphic, and Sedimentary rock.
Molten material, known as magma solidifies to become an igneous rock. The rock will sometimes undergoes process known as weathering, this will erode, be transported and deposited as sediment. If this unconsolidated material becomes lithified (or cemented) it becomes a sedimentary rock. Or after solidification, it may be exposed to extreme heat and pressure (without melting) and metamorphism occurs, resulting in a metamorphic rock.