Wave-particle interactions refer to the behavior of particles, such as electrons or photons, when they encounter waves, like light or sound waves. These interactions can lead to phenomena such as diffraction, where waves bend around obstacles, or interference, where waves combine to form new patterns. In quantum mechanics, particles exhibit both wave-like and particle-like properties, a concept known as wave-particle duality. This means that under certain conditions, particles can behave like waves, spreading out and overlapping, while in other situations, they act like discrete particles, localized in space. This duality is fundamental to understanding the behavior of matter at the microscopic level.