Canning is a method of food preservation that involves placing foods in jars or cans and heating them to a temperature that destroys microorganisms that could be a health hazard or cause the food to spoil. The high heat destroys microorganisms and inactivates enzymes to preserve the safety and quality of the food. The canning process also drives air from the jar during heating, and as it cools, a vacuum seal is formed, which prevents air from getting back into the product, bringing with it microorganisms to recontaminate the food.

The canning process involves several stages, including cleaning and preparing the raw food material, blanching it, filling the containers, usually under a vacuum, closing and sealing the containers, sterilizing the canned products, and labeling and warehousing the finished goods.

There are three safe ways of canning, depending on the type of food being canned: boiling water bath method, atmospheric steam canner method, and pressure canner method. Pressure canning is the only safe method of canning low-acid foods, such as vegetables and meats, because it destroys Clostridium botulinum bacteria, which can produce the deadly botulinum toxin.

Proper canning practices include washing the product carefully, packing the food according to directions, wiping off the rims of the jars with a clean, damp cloth, and using the correct canning method. It is important to use recipes from reliable sources because these recipes have been tested for safety and quality.