The rote definition of matter as anything that has mass and occupies space is also the most apt one. Yes, matter is indeed as it is described without the complex differentiations that follow most of the other science-based concepts. But what can be said of the different physical forms that the matter takes, known as the states of matter? Much of the distinction between the states of matter arises from the arrangement of the constituent particles. And the constituent particles are the atoms, which are so small that our naked eyes are unable to even see them. Even a sheet of paper is at least a million times thicker than the size of an atom. The proximity of an atom of a substance with another decides the state of matter the substance would be in.
In normal life we encounter the three very evident states of matter: solid, liquid and gas. The fourth basic state of matter is plasma.
Solid as a rock
In the solid state, the atoms are very closely jammed together. They attract their neighboring atoms so strongly that there is no free movement possible. The only thing they are allowed to do is move to-and-fro about their fixed location by vibrating. However, this in turn allows the solid to have a particular shape and size. You cannot compress the solid by such an amount that something drastic happens which alters its behavior, without breaking it. When the solid state is supplied with enough energy, a transition to liquid state takes place.
Liquids are shape-shifters
The liquid state can similarly be explained, with the concept of atom, as the state in which atoms are not so strongly held together by one another. There is some relaxation in the restrictions the atoms impose on their neighbors by virtue of their attractive force. Thus, liquids can flow and can take the shape of the container in which they are kept. The shape of the liquid is not defined. On heating the liquid or providing it with some form of energy, it goes into the gas state.
Gases can be compressed in a can
The case of gases is one in which the constituent particles are quite spread out due to the weak force of attraction between them. The gases not only take the shape of the container in which they are kept but also expand to fill the whole of the container. This means it is possible to compress the gas into a much smaller volume by trying to force the constituent particles together. Gases can be heated and supplied energy by other means to take them to the plasma state.
Plasma is magic lightning
Plasma is another fundamental state of matter, without a well-defined shape or size like the gaseous state. When you observe a lightning strike, you are actually observing light flowing through a plasma channel of air that has been heated to very high temperatures, forcing a conversion from gaseous to the plasma state of matter.