BJT DefinitionA Bipolar Junction Transistor (BJT) is defined as a three-terminal semiconductor device used for amplification and switching.Applications of Bipolar Junction TransistorThere are two types of applications of bipolar junction transistor, switching and amplification.Transistor as a SwitchIn switching applications, a transistor operates in either the saturation or cutoff region. In the cutoff region, the transistor acts as an open switch, while in saturation, it acts as a closed switch