PNP and NPN. The NPN is easiest to manufacture and implement.
Not really a third type is the Darlington Pair, but students tend to blush when they talk about it. It has a higher gain and is contructed from two NPN's.
The two basic types of transistors are the NPN transistor and the PNP transistor. Certainly there are many other semiconductor devices, but these are arguably the two basic ones.
transistor employin flow of both electron and holes for conduction is bipolar junction transistor.they are bipolar in nature.a bjt has two pn junctions, one between emitter and base and the other...