Food is a fundamental facet of life for all human beings to meet their metabolic needs for survival, development, and reproduction. But food, just like any other organic matter, is transitory, i.e., it degrades with time. Food spoilage is any alteration that makes the food unfit for human consumption. A multitude of conditions combine to cause food spoilage. Microorganisms, which compete for nutrients, cause most food spoilage. Fresh fruits, vegetables, and meat provide a rich source of nutrients that heterotrophic microorganisms find enticing. Since they are ubiquitous and disseminate as resistant air, water, or soil-borne spores, they readily colonize, multiply, and produce toxic and unpleasant compounds on the unguarded foods. Food spoilage can also be induced by physical and chemical changes, such as oxidation of certain food ingredients, insects or pest infestation, or breakdown by endogenous enzymes. Food storage and preservation have long been a fundamental concern in nourishing humankind. Civilizations have shown their ingenuity in devising practical and novel methods for the same. The following chapter discusses food spoilage, food classification depending upon stability, agents causing food spoilage, food preservation and storage.