states (of matter)
Depending on parameters like temperature or pressure, one and the same portion of matter can occur in different states with greatly varying physical properties. The most important states of matter are the solid, liquid, gaseous and plasma states (the latter three forms of matter are also called fluid). At very low temperatures, atoms bind together to form a solid body with a definite shape. As temperature increases, many solid bodies melt, giving a liquid or, at even higher temperatures, a gas, an ensemble of atoms and/or molecules scurrying wildly to and fro. With a further increase in temperature, a plasma state can be reached, atoms desintegrating into atomic nuclei and electrons.