Ever since accretion and formation as a rocky planet in our solar system some 4.56 billion years ago, our dynamic planet Earth has been in an ongoing evolution. The migration and collision of rigid tectonic plates, driven by mantle convection, have fostered intense production and reworking of continental and oceanic crust from the beginning of plate tectonic processes. Metamorphic rock is the result of changes in physical and chemical circumstances transforming a protolith, which might be sedimentary, magmatic, or metamorphic. As a result, a metamorphic rock may retain a wealth of information about its protolith as well as the retention of diverse rock records from many partial re-equilibration stages of a single or multiple metamorphic cycle. Only glimpses of the cumulative processes are preserved in mineral assemblages, chemistry, and microstructures due to their intricacy. Studying rock samples that best preserve this fractured metamorphic record, as well as developing the finest petrological methods for analyzing them, is therefore critical.