Freon is a registered trademark of The Chemours Company, which uses it for a number of halocarbon products. They are stable, nonflammable, moderately toxic gases or liquids which have typically been used as refrigerants and as aerosol propellants. These include the chlorofluorocarbons (CFCs) that cause ozone depletion (such as chlorodifluoromethane), but also include newer refrigerants which typically include fluorine instead of chlorine and do not deplete the ozone layer. Not all refrigerant is labelled as "Freon" since Freon is a brand name for the refrigerants R-12, R-13B1, R-22, R-502, and R-503 manufactured by The Chemours Company.
See Also
Azeotrope
Cycle of Temperature
heat engine
Heat pump and refrigeration cycle
Refrigerant
refrigerator
Stirling Engine
working fluid