What causes a light-emitting diode (LED) to emit light?

A light-emitting diode (LED) functions much like a standard semiconductor diode, meaning it allows electrical current to flow easily in only one direction. This intended, conductive direction is known as "forward current" or forward bias. When forward current flows through the LED's semiconductor junction, electrons and electron holes recombine. This specific chemical and electrical recombination process releases energy in the form of photons, which we perceive as light. If the polarity is reversed, the diode blocks the current (reverse current), and no light is emitted. The distractors involving RF signals are incorrect because basic LED illumination relies on direct current flowing through the junction, not on coupled radio frequency energy.