Solids, liquids and gases are called the three states of matter. Liquids can flow or be poured easily. They are not easy to hold. Liquids change their shape depending on the container they are in.

Sorry! Anyway, some changes we make to materials are irreversible. So once the change has happened, we can't go back again. If you crack an egg in a frying pan and heat it up, that's an irreversible ...