A graben is a wedge-shaped block of rock that drops between a pair of normal faults. The normal faults around the graben are called horsts. This resembles two mountains separted by a flat valley. The mountains are the horsts while the valley in between is the graben. Normal faults and grabens are typical of divergent boundaries at mid-oceanic ridges and continental rifts where the crust is stretched.
Reverse faults occur when the hanging wall has moved up relative to the footwall.
This is due to compressional pressure pushing the crust together and tends to shorten the distance between the crust. A special kind of reverse fault that is nearly horizontal is called a thrust fault. It's made of a very low-angle reverse fault. Folds, reverse faults, and thrust faults tend to occure at most convergent plate boundaries where two plates collide. This allows the rocks on opposite sides of the fracture to move horizontally past each other.