The Young slit experiment, performed by Thomas Young in 1801, is an iconic demonstration of the wave nature of light. Young passed a beam of light through two thin parallel slits, projecting the result onto a screen. Rather than two distinct bands of light, he observed an interference pattern: alternating light and dark bands. This phenomenon proves that light behaves like a wave, with the peaks and valleys interfering to create these patterns. Later, this experiment was also adapted to study the behavior of particles, revealing their wave-particle duality, a key concept in quantum mechanics.