I've heard a lot about plasma, but what IS it?

It's ionized gas, but what does that mean? What is different between a gas and plasma? What are its characteristics?
A plasma is a gas into which sufficient energy is provided to free electrons from atoms or molecules and to allow both species, ions and electrons, to coexist [1, 4]. Plasma consists of free-flowing electrically charged particles and is affected by electric and magnetic fields in ways not seen in other forms of matter [3]. It can be created by energizing a gas to the point that some of the electrons break free from, but travel with, their nucleus [4]. Unlike the phase transitions between the other three states of matter, the transition to plasma is not well defined and is a matter of interpretation and context [5].
Plasma, in physics, is an electrically conducting medium in which there are roughly equal numbers of positively and negatively charged particles, produced when the atoms in a gas become ionized [1, 2]. It is sometimes referred to as the fourth state of matter, distinct from the solid, liquid, and gaseous states [1]. The uniqueness of the plasma state is due to the importance of electric and magnetic forces that act on a plasma in addition to such forces as gravity that affect all forms of matter [2]. Plasma is made when gas is heated until its electrons have sufficient energy to escape the hold of the positively charged nuclei [3]. As molecular bonds break and atoms gain or lose electrons, ions form [3]. Plasma can be made using a laser, microwave generator, or any strong electromagnetic field [3]. Plasma consists of free electrons and positively charged ions (cations) [4]. It reacts to electromagnetic fields and conducts electricity, whereas gases are electrical insulators [4]. Like a gas, plasma has neither a defined shape nor volume [4]. When plasma is exposed to a magnetic field, it may assume structures, including layers, filaments, and beams [4]. 