For someone who lives at a high altitude or who cans and preserves foods, a pressure cooker is an asset. In Denver, for instance, water boils at 203F instead of 212F, as it would, say in San Diego. Consequently, any given ingredient takes longer to cook in Denver. The predicament of having a relatively low boiling point for water can be solved with a pressure cooker, since it allows water to reach a temperature of up to about 250F.
Water inside a pressure cooker boils at a high temperature because the atmospheric pressure within the pot is increased. The ingredients also cook faster because the steam - most of which does not escape the pot - is a better heat conductor than air. And thanks to the increased pressure within the pot, that steam more aggressively penetrates the food.
The higher temperatures of pressure-cooking also benefit the home canner because the heat can more effectively destroy the pathogenic microorganisms that contaminate the food. This capacity is particularly critical when canning low-acid ingredients. For other cooks, a pressure cooker can shorten the cooking process and thereby reduce fuel expenditure, compared with the non-pressurized boiling method. From a gourmet's viewpoint, however, the texture of pressure-cooked foods like meat still resembles that of ordinary boiled food.