Liquid is one of the three main states of matter, along with solid and gas. A liquid flows and takes the shape of whatever container holds it, but unlike a gas, it doesn't expand to fill the entire space. Pour water from a tall glass into a wide bowl, and the water changes shape perfectly to match its new container.

Think about the difference: ice (solid) holds its shape, water (liquid) flows and adapts, and steam (gas) spreads out to fill a room. Liquids happen when molecules move fast enough to slide past each other but not so fast that they fly apart completely. That's why you can pour juice, stir soup, or watch rain run down a window.

Common liquids include water, milk, oil, and gasoline. Some surprising things are liquids too: honey flows incredibly slowly, but it's still a liquid.

In everyday conversation, people use liquid to describe things that flow or move smoothly. Money kept as cash instead of invested in property is called liquid because it can move quickly from person to person, like water flowing from container to container.