Water freezes at 0 C. When water freezes it changes from a liquid to a solid. Molecules in a solid are packed tightly together. A solid can't change its shape nor can it change its volume.
The melting point
The melting point is just like the freezing because they both change at 0 C. When water melts it goes from solid to a liquid. The molecules have a little more room to move around . A liquid takes the shape of its container.
The boiling point
The boiling point of water is 100 C. When water boils it makes steam that evaporates . This transaction goes from a liquid to a gas. The molecules in a gas can go where ever they want. A gas has no definite shaped or volume.