Refrigerator and Refrigerant

A "Refrigerator" is a reversed heat engine or heat pump which pumps heat from a cold body and delivers it to a hot body.the substance which works in a heat pump to extract heat from a cold body and delivers it to a hot body is called "Refrigerant"

Refrigeration

The term " refrigeration" may be defined as the process of reducing heat from a substance under controlled conditions.(or) the refrigeration is a continued extraction of heat from a body whose temperature is already below the temperature of it's surroundings.
example: suppose if some space is to be kept at -4 degree centigrade (269.15K),we must continuously extract heat which flows into it and also the heat  which is brought into it with the articles or materials stored after the temperature is once reduced to - 4 degree centigrade (or) (269.15K).So in a refiregator ,heat is virtually being pumped from a lower temperature to a higher temperature.According to Second Law of Thermodynamics,this process can only be performed with the aid or help of some external work.Here we can say electric power (or) supply of power as some external work,It is reguarly required to drive a refigerator.