Canning is a preservation technique that is a part of making jam. But once you break the seal on the jar, the food in the jar is exposed to the air and won't la

Canning is a preservation technique that is a part of making jam. But once you break the seal on the jar, the food in the jar is exposed to the air and won't last as long. Regarding jam, I think it probably depends on the kind of jam. I usually get the stuff with whole strawberries that I spread with a spoon. I'm sure the typical American jelly will last a long time unrefrigerated, but that seems to be less common in my part of Canada.