How does a npn transistor conduct?

An NPN transistor conducts when a small current flows into the base terminal, creating a potential difference that allows electrons to move from the emitter (n-type material) to the collector (also n-type). This movement of electrons allows a larger current to flow from the collector to the emitter, enabling the transistor to amplify signals. The base-emitter junction must be forward-biased, while the base-collector junction is reverse-biased for the transistor to operate effectively in the active region.