Interference is an effect that occurs when two or more waves overlap. In general, the individual waves do not affect one another, and the total wave amplitude at any point in space is simply the sum of the amplitudes of the individual waves at that point. In some places, the two waves may add together, and in other places they may cancel each other out, creating an interference pattern that may look quite different than either of the original waves. Quantum mechanical wavefunctions can interfere, creating interference patterns that can only be observed in their corresponding probability distributions.