What is the process by which rocks are transformed into other types of rocks?

Most rocks start of from sediments like bits and pieces of dirt, bone and smaller pieces of rock. Then it settles and forms together to form a sedimentary rock, at this point if it undergoes heat or pressure then it can become a metamorphic rock. The other option is once it heats up it can melt and become magma from then it cools off and becomes a igneous rock.