Definition of solid liquid gas and plasma?

We know that solid, liquid, gas and plasma are the "big four" states of matter. The differences between them lie mainly in the energy of the material being looked at. If we consider water, for example, it is cold when it is the solid we call ice. Warm it up and it melts to become the liquid with which we are all familiar. Warm it even more and it turns into the gas we call water vapor or steam. By superheating it, we can even supply so much energy to it that one or more electrons will leave the atoms in the molecule. This creates a plasma. The other differences between the states of matter involve their shape. Solids are just that -- solid, and they maintain their shape. Liquids take the shape of their container because they are fluids. Gases are fluids as well, and will "escape" if not completely confined in some way. This is in contrast with a glass of liquid water, which stays in the glass even though there is no lid on it. The changes between the states of matter are physical changes (as opposed to chemical ones), and they are energy dependent. Think this through and it will make sense and lock in.