Canning is a method of preserving food in jars or cans using a controlled heat process and an airtight seal. Correct processing makes suitable foods shelf-stable until opened; a sealed lid alone does not show that food was processed safely.
For home canning, the method depends on the food's acidity. Low-acid foods, including most vegetables, meats, poultry, seafood, and mixtures containing them, require pressure canning. Boiling-water canning is appropriate only for suitable high-acid or properly acidified foods prepared according to a tested recipe.
Use a current, research-tested recipe and follow its jar size, preparation, processing time, pressure, and altitude adjustments. Do not substitute a slow cooker, oven, or ordinary electric multicooker for a pressure canner. Refrigerate food after opening when the recipe or product label requires it.
See the National Center for Home Food Preservation's canning guidance for tested procedures.