This document discusses the three main types of rocks - igneous, sedimentary, and metamorphic rocks. It provides examples of how each type of rock is formed, such as igneous rocks forming from cooling magma or lava, sedimentary rocks forming from the cementation of tiny grains like sand, and metamorphic rocks forming from limestone exposed to heat and pressure. The document aims to help identify different rocks and understand how they are formed in preparation for a test on the topic.