In the very early days of refrigeration, there were blocks of ice out of rivers and lakes for cooling and no refrigerant was needed. Then later, when mechanical refrigeration came along, refrigerants such as sulfur dioxide and ammonia and the fluorocarbons also were introduced. The latter two — ammonia and f-gases — are still being used.
Of the fluorocarbons, the choices were pretty simple: CFCs -11, -12, and -502. It is not so simple these days. First of all, there are some systems still running on CFCs. But a lot more refrigeration systems are running on HCFCs like -22 and -123. Then there are a lot systems running with HFCs like -410A, -134a, -507, and many, many, many more HFC refrigerants.