Everything around us exists in one of the three states of matter. Things can be solid, liquid or gas!
Take a look around you now. You can probably see lots of things that would be classed as solids. Your chair, your desk, a pen..... maybe you can see a cup or a plastic toy. All solids! We can tell they're solids because they can be held in your hand (if they're not too heavy!) as they have a fixed shape.
Liquids on the other hand, cannot be held in your hand - unless they are in a container, like a bottle or a cup. The milk you pour on your cereal, the juice you drink when thirsty, the rain that falls when it's a wet and grey day - all liquids. We can tell they are liquids because they can flow, or be easily poured. They can also change shape depending on what container they are in. Impressive hey!
The reason why solids and liquids have quite different properties is because of the way their particles are arranged.
In a solid, the tiny particles that make up the solid are very close together in a neat regular arrangement, all touching each other and moving only by vibrating on the spot. They cannot move much at all, which explains why solids have a fixed shape.
The particles in a liquid are arranged in a more random way. They are close together, most of them touching each other, but there are some small gaps. So the particles can move around a little, over each other, allowing liquids to flow and be poured. This is the reason why liquids take the shape of the container they are in.
Think you know the difference between solids and liquids now? Great! Then let's take a look at a few questions about them.