Liquid matter is one of the states of matter found in nature. At standard conditions for temperature and pressure, liquids can flow and can take on the shape of the container that they are poured into. However, liquids do have a definite volume.
At standard conditions for temperature and pressure, some examples of substances that are in the liquid state are water, oil, mercury, alcohol and acetone. Mercury is the only metal element that exists as a liquid at room temperature. Liquids are not easily compressible at standard conditions, but may be compressible at very high pressures.
The molecules in liquids have more freedom of movement than those of solids. Liquids have certain physical properties, including density, melting and boiling points. A mechanical property of liquids is viscosity. Viscosity is a liquid's resistance to flow. For example, honey flows more slowly than water because its viscosity is greater.
When heated, liquids expand. As they reach their specific boiling points, liquids change into gases. Conversely, a decrease in temperature causes liquids to contract when they reach their freezing point. At this point, there is a change of phase, and liquids can become solids, such as water turning into ice in a freezer.
Liquids have various applications, including as lubricants, solvents and in hydraulic systems or devices. Paint thinners are solvents. A device such as a thermometer, which measures temperature, contains mercury.