Refrigeration is the action of creating cooling conditions by removing heat. It is used for preserving food by slowing bacteria growth.

• Around 1000BC, the Chinese used to cut and store ice.
• Five hundred years later, the Egyptians and Indians left earthenware pots out during cold nights to make ice.
• In the 17th century, it was found that saltpeter dissolved in water creates cooling conditions.
• In the 18th century, Europeans collected ice in winter, salted it, wrapped it in flannel, and stored it underground for months. Ice was even shipped around the world.
• People also used cool cellars or placed goods underwater.
• Others built ice boxes out of wood, lined with tin or zinc, and insulated with cork, sawdust, or seaweed, and filled with snow or ice.

• 1720s. Scottish doctor William Cullen saw that evaporation had a cooling effect.
• 1748. Cullen demonstrated his ideas by evaporating ethyl ether in a vacuum.
• 1805. Oliver Evans designed a refrigeration machine that used vapor instead of liquid.
• 1820. English scientist Micahel Faraday used liquefied ammonia for cooling.
• 1835. Jacob Perkins, who worked with Evans, patented a vapor-compression cycle using liquid ammonia.
• 1842. John Gorrie, an American doctor, built a machine similar to Evans's design to artificially create ice and cool down patients with yellow fever.
• New and improved refrigeration ideas continued to be developed, including Albert Einstein's idea of an environmentally friendly refrigerator with no moving parts that did not rely on electricity.
• By 1920, refrigerators were considered essential in American homes.