The art of processing food to stop or at least greatly slow down the normal processs of microbial decay.
Bacterial growth usually requires moisture; so the simplest process is drying, whether in air or by heat. The drying may be aided by smoking the food, which besides removing moisture, adds chemicals that add flavour and/or inhibit microbial growth.
Alternatively, while not removing much moisture, adding large amounts of salts or sugars will raise the osmotic pressure of the water in the food to the point that decay is slowed. A similar process is pickling, where the food is made too acidic for spoilage organisms: sometimes as a result of fermentation of some other organism. e.g. Sauerkraut
Alternatively the food can be frozen to stop spoilage; or the food is sterilised by cooking and sealed in airtight containers in the process called canning to prevent contamination by further organisms.
Many of these techniques, as in the curing of bacon which is dried and has various salts added.