Faults are cracks in the Earth's crust caused by stress and movements within the crust. Faults can range in size from millimeters to thousands of kilometers long and cause earthquakes or creeping movements. Different types of faults include normal faults, reverse faults, and strike-slip faults, each producing distinct landscapes and forming either the hanging wall above the fault plane or foot wall below. The San Andreas fault is an example of a major strike-slip fault in California.