Incremental forming process is a relatively new sheet metal forming process with superior formability characteristics over other conventional forming processes. This paper reviews the reasons for improved formability in incremental sheet forming process. Further, the effect of process parameters on formality has been discussed. The formability in incremental forming is generally evaluated by maximum formable wall angle and fracture forming limit diagram. Different procedures adopted by the researchers to find the maximum wall angle and construction of fracture forming limit diagram have been discussed. The formability assessment in other variants of ISF processes such as multi stage incremental forming and incremental hole flanging are also presented