What is the difference between PNP and NPN transistors?

A positive voltage is applied to an NPN transistor's collector terminal to cause current to flow from the collector to the emitter. A positive voltage is applied to the PNP transistor's emitter terminal to cause current to flow from the emitter to the collector.

In everyday life, what is the function of a transistor?
Transistors can be found in almost any electronic device, from stoves to computers, pacemakers to airplanes. 9. The military used the transistor's high-power radio frequency (RF) capabilities in radar and hand-held two-way radios.