A fault is a fracture or zone of fractures in the Earth’s crust along which movement has occurred. Faults can range in size from a few centimeters to thousands of kilometers and are categorized into types such as normal, reverse, and strike-slip based on the direction of movement. Faults are significant in understanding tectonic processes, earthquake generation, and the structural evolution of the Earth’s crust.
Source Twiss, R. J., & Moores, E. M. (2007). Structural Geology. W. H. Freeman.