Our ancestors devised many methods of preserving their harvest out of necessity. They did not have the luxury of having fresh food shipped, sometimes thousands of miles, to the grocery nearest them. Nor did they have freezers that would hold the food cold for months at a time (except in the coldest climates where it was kept in attics or outside).
Food Preservation includes many different methods: Canning, Freezing, Dehydrating, Cooked and Frozen as meals, Smoking, and Fermenting to name a few. When choosing a method or methods to use for a particular fruit or vegetable coming out of your garden or bought bulk at your local farmers market you have to decide how you are going to use this product and primarily how you prefer to eat it. There is no sense dehydrating everything if you don't like reconstituted dried foods or canning if you hate, well canned peas for example. Sometimes the way you use that particular food will dictate how you preserve it.