Why bipolar transistor

Why bipolar transistor?
With the bipolar transistor two kind of carriers are
involved: electrons and holes. Hence, bipolar transistor.
In an n-material, the electrons are the majority carriers.
In a p-material, the holes are the majority carriers.
Since the bipolar transistor consists of two pn-junctions,
there are two possible constellations:
pnp and npn, whereas the npn constellation is most
common.