Plasma is often referred to as the fourth state of matter, along with solid, liquid, and gas). It is a state of matter in which an ionized substance becomes highly electrically conductive to the point that long-range electric and magnetic fields dominate its behavior). Unlike solids, liquids, and gases, plasmas have no fixed shape or volume and are less dense than solids or liquids. However, unlike ordinary gases, plasmas are made up of atoms in which some or all of the electrons have been stripped away and positively charged nuclei, called ions, roam freely. Plasma is a charged gas, with strong Coulomb or electrostatic interactions. Atoms or molecules can acquire a positive or negative electrical charge when they gain or lose electrons, a process called ionization. Plasma makes up the sun and stars, and it is the most common state of matter in the universe as a whole.

To summarize, plasma is a state of matter in which an ionized substance becomes highly electrically conductive to the point that long-range electric and magnetic fields dominate its behavior. It is often referred to as the fourth state of matter, along with solid, liquid, and gas. Unlike solids, liquids, and gases, plasmas have no fixed shape or volume and are less dense than solids or liquids.