A liquid's molecules can move around more than in solids. This means a liquid can change shape and flow, although, like a solid, it still takes up the same volume. Liquids cannot be stretched or cut into pieces in the way that some solids can. A liquid's molecules also cannot be squeezed together. So when a liquid flows through a narrow space such as a pipe, it pushes against the wall of the container. In other words, its pressure is greater.

Surface tension

The molecules of liquids are attracted to one another. At the liquid's surface, this attraction is revealed as a force called surface tension. It is as if the liquid has a stretchy skin on its surface. This "skin" enables some insects, such as water striders, to move about on the surface of water.

Some liquids can flow more easily than others. Water, for example, flows more easily than oil. Viscosity, or runniness, is the term used to describe this property. In a runny liquid like water, molecules slide over one another more easily than those of a more viscous liquid like oil.