why we call bjt as bipolar junction transistor

 BJT(bipolar junction transistor)

Bipolar means two type of charge carriers which are electrons and holes .For working of  transistor we require both holes and electrons as Ib(base current) is due to recombination of holes and electrons in base region and this Ib is required for transistor to be in active region .So this Ib comes from recombination of electrons and holes means we require both holes and electrons so we call it as bipolar junction transistor