Refrigeration has become commonplace in the world after the arrival of the refrigerator. But before it's widespread use, what methods were used to preserve perishable food in the past?

    There were a variety of methods in the past, with different levels of practicality. Humanity has long since discovered fire and that it can be used to heat things up. However, cooling anything outside of winter, especially in the heat of summer, was a true technical challenge for thousands of years.

    A way to explain why it was much more difficult to find ways to cool than to heat is the similar to light and dark. From a physics standpoint, dark is really just the non existence of light. Similarly, cold is lack or non existence of heat (Rees, J. (2013)). In short, it's much easier to produce heat than to remove it.

	Before the technology existed to cool foods, the most common ways of preserving meat were salting and drying (specifically meat). Other foods had could be canned, but all foods had their own individual ways of storing them, which always had disadvantages, especially in causing food poisoning over a period of regular consumption (Briley, G. C. (2004)).
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    After the breakthrough of refrigeration, food could be preserved longer and more conveniently, and thus, not just for individual consumers but was also very economical for food businesses. In addition to this, refrigerators and their technology have gotten increasingly more efficient and complex over time.

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