Liquids are materials that can flow, such as water, mercury, or maple sap.
Just because something is liquid does not mean it will stay a liquid. For example, if it gets cold enough, liquid water will turn into solid water, a form we call ice. Alternatively, if it is heated enough, liquid water will turn into gaseous water, steam. These three states of matter can change from one to another, depending on how active their molecules are. Now, in a situation such as paint drying there are two phenomena occurring.