First of all, there are two main types of MOSFETs: either enhancement or depletion mode. Enhancement modes function in a normally off condition. When a voltage is applied between the gate and source, they turn on. Depletion mode MOSFETs are normally on, and when a Vgs is applied they turn off. Looking at the enhancement mode devices, there are two types; N-channel and P-channel. N-channel devices have positive voltages and positive currents. Alternately, P-channel MOSFETs have negative currents and negative Vgs. P-channel MOSFETs are still used in the market, but less than the N-channel. Focusing on the N-channel product domain, normally N-channel MOSFETs are classified into main categories; low-voltage MOSFETs range from 0 to 200V , above 200V is the domain of the high-voltage MOSFETs.