The document defines key terms related to the rock cycle, including the three main types of rock - igneous, sedimentary, and metamorphic. It explains that igneous rock forms from cooling magma, sedimentary rock forms through compaction and cementation of sediments, and metamorphic rock forms from changes to existing rock by heat and pressure. The rock cycle is also defined as the process where rocks slowly transform between these three types over time through weathering, erosion, deposition and metamorphism.