Metamorphism is the process by which rocks undergo changes in mineral composition, texture, and structure due to high temperatures, pressures, or chemically active fluids. This can occur deep within the Earth's crust or at the Earth's surface. Metamorphic rocks are formed when existing rocks are subjected to these conditions, causing the minerals within them to reorganize and recrystallize. Metamorphism can occur in a variety of geological settings, such as along fault zones, in subduction zones, or during mountain-building processes. Studying metamorphism can provide valuable insights into the history of Earth's crustal evolution, as well as help us understand the processes that shape the Earth's surface over time.