This video shows how the ripple tank can be set up to show waves emanating from two separate sources. In this case each is a point source. This generates waves from two locations and the waves interact with each other. We say that the waves are superposed, meaning that both waves affect the movement of water in the tank and the overall movement depends on the effects of the two waves combined (or superposed).

Superposition of waves is an important idea. It explains how waves can interfere with each other, canceling each other's effect. It also explains how waves can augment each other, creating a larger wave. Superposition of electron waves is the fundamental reason for chemical bonding.