Most people are familiar with three states of matter: solid, liquid and gas. Actually, if you dig into the world of physics, there are several more, but for now we will only add plasma to the list, and we will look at the first three states before talking about plasma.
Things like rocks, wood and ice are solid. Solids stay the same size and shape, no matter what container we put them in.
Things such as alcohol, oil, and water are liquids. They stay the same size, but they change their shape to fit their container.