A thrust fault is a geological fault in which rocks on one side of the fault plane are pushed and placed on top of the rocks on the other side. This type of fault is commonly found in regions undergoing crustal compression, such as mountain-building areas. There are several synonyms for the term "thrust fault." One is a compressive fault, which describes the stress that compresses the rocks and results in the fault's formation. Another synonym is a reverse fault, which denotes the opposite direction of movement in a normal fault, where the hanging wall moves down. Other common phrases include a thrust zone, thrust belt, or decollement zone, which all refer to areas where thrust faults are concentrated.