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Liquids, such as water or oil, can form droplets held together by surface tension. Surface tension is a result of cohesive forces between the molecules in the liquid, causing the surface to behave like an elastic membrane. Because liquid droplets are relatively simple to observe and manipulate under varying conditions, they have been a subject of interest for experimentalists for over two centuries. At the surface of a liquid, the molecules are more attracted to each other than to the air molecules above them. This creates unique properties at the surface and influences the shape of the droplet. Surface tension helps prevent the molecules from spilling or dispersing. The size of droplets formed from a dropper varies depending on the type of liquid. For instance, oil droplets are smaller than water droplets, even when dispensed from the same dropper. This is because the molecules in each liquid have different levels of attraction to one another, resulting in different surface tensions for each liquid.