The multi-gate transistors such as Fin-FETs, Tri-gate FETs, and Gate-all-around (GAA) FETs are remarkable breakthrough in the electronic industry. 3D Transistor is taking the place of the conventional 2D planar transistor for many reasons. 3D transistors afford more scalability, energy efficient performance than planar transistors and increase the control on the channel region to reduce the short channel effect, which enables us to extend Moore’s law to further extent. In this paper, we will present a review about their structure, operation, types and fabrication.