Matter can exist in four main forms - solid, liquid, gas, and plasma - depending on how tightly or loosely the atoms are packed together. Solids have closely-packed atoms, liquids have loosely-packed atoms, gases have widely-separated atoms, and plasma consists of free electrons in space. There are also other potential states of matter like super solids, which are theorized to have no friction. The document provides an overview of the standard forms of matter and their distinguishing atomic structures.