How does wave-particle duality apply to electromagnetic radiation?

Wave-particle duality is the concept that electromagnetic radiation exhibits both wavelike and particle-like characteristics depending on the experimental conditions.12

In classical physics, electromagnetic radiation is described as a wave consisting of mutually linked, time-varying electric and magnetic fields that propagate through space. This wavelike nature is evidenced by phenomena such as interference and diffraction, where waves from different sources reinforce or cancel one another.324

Conversely, quantum theory reveals that radiation also behaves as a particle—specifically as discrete packets of energy called photons. This particle-like behavior is demonstrated in interactions with matter, such as the photoelectric effect, where light ejects electrons from a material, and the Compton effect, which confirms the corpuscular nature of radiation.35164

This duality implies that radiation is not exclusively one or the other; rather, its wave properties are typically apparent during propagation, while its particle properties are revealed during interactions with matter. This paradoxical behavior was eventually reconciled through the development of quantum electrodynamics.24