A raindrop is born in a cloud. There, water vapor accumulates on a dust particle until gravity can take over and pull the raindrop toward the Earth. As the raindrop falls, countless other raindrops fall with it. Sometimes a raindrop may merge with another drop, and other times it may split into two or more drops. The wind can toss the raindrop. The raindrop can run into a tree and explode upon impact. The raindrop can land on a lawn, be absorbed into the roots of the grass, and turn back into water vapor as it evaporates from the leaves. But this raindrop experiences none of that. This raindrop lands in a river that leads to an ocean. In an instant, just as it was born into its unique, tiny form, the raindrop is returned to the great mass of water that gives life to the Earth.