Wave-particle duality is a fundamental concept in quantum mechanics that describes how particles, such as electrons and photons, exhibit both wave-like and particle-like properties. For instance, light can behave like a wave, spreading out and creating interference patterns, but it can also act like a particle, being absorbed or emitted in discrete packets called quanta. This duality challenges our classical understanding of physics, where objects are typically categorized as either waves or particles. Experiments, such as the double-slit experiment, demonstrate this phenomenon, revealing that the behavior of particles can change depending on whether they are observed, highlighting the complex nature of reality at the quantum level.