A refrigerant is a special substance that absorbs heat from one place and releases it somewhere else, making refrigeration possible. Inside your refrigerator, refrigerant flows through coils and tubes, constantly cycling: it evaporates to absorb heat from inside the fridge (making the interior cold), then gets compressed and condenses to release that heat outside the fridge (which is why the back of a refrigerator feels warm). This process repeats continuously, keeping your food cold.

Refrigerants work because they can change between liquid and gas at temperatures useful for cooling. Early refrigerators used substances like ammonia, which worked well but can be dangerous if they leak. In the 1930s, scientists invented new kinds of refrigerants, such as CFCs, which seemed perfect until researchers discovered they were damaging Earth’s ozone layer. Today, many refrigerants are designed to be safer and more environmentally responsible.

The same principle works in air conditioners, which use refrigerants to pull heat out of your house and release it outside. Even ice rinks rely on refrigerant systems to keep the ice frozen. Without refrigerants, we wouldn’t have reliable ways to preserve food, cool buildings, or create ice on demand.