Gas is one of the main types of matter. It takes up the full shape of anything that it is in. The gas molecules that spread out cause the gas to take up space.
A liquid is another type of matter. A liquid is anything that flows. It can change shapes but it takes shape of the container it is in. The molecules in liquid are close together but free to move around.
A solid is the last type of matter. A solid has its own shape. It keeps it's own shape unless it is crushed. Molecules in solids are tightly packed and they can not move around.