Refrigeration is the process of producing low temperatures. It takes place when heat is removed from a substance. Cooling can be achieved with ice or snow, or by machines. For thousands of years, people have used some kind of refrigeration to cool beverages and preserve food. Since the mid-1800's, refrigeration has been widely used to keep food from spoiling.

Today, people store foods in home refrigerators and freezers. Grocery stores and food companies may use refrigerated display cases, freezing rooms, and cold-storage warehouses. Fresh foods are carried long distances in refrigerated trucks, refrigerated railway cars, and refrigerated compartments of ships. People on camping trips can keep food fresh for days with portable refrigerators installed in their vehicles.

Refrigeration has many uses beside preserving food. Air conditioning depends on refrigeration to cool homes, offices, theaters, stores, and automobiles. Refrigeration makes it possible to store serums, vaccines, blood plasma, and other lifesaving medical supplies. Drug companies use refrigeration to make penicillin and other drugs. Cleaners and fur companies store furs in refrigerated vaults to protect them from moths and to keep the furs in good condition. Florists refrigerate cut flowers to preserve their fresh appearance. Drinking fountains supply cold water, and ice machines provide blocks, cubes, flakes, and chips of ice. Ice plants and skating rinks use refrigerating machines to manufacture ice. Industry uses refrigeration in the processing of rubber, lubricants, and steel, and in producing frozen fruit juices, candy, photographic films, ice cream, chemicals, and many other products.