Food preservation is the set of methods used to prevent food from spoiling, extending the time it stays safe and palatable. Traditional techniques — salting, smoking, drying, fermenting, and pickling — work by making conditions hostile to microbes, usually by removing water or adding acid. Modern methods add heat treatments such as pasteurisation, canning, and UHT processing; freezing and chilling, which slow microbial growth; modified-atmosphere and vacuum packaging, which limit oxygen; and chemical preservatives such as sorbates, benzoates, and nitrites, all used within legal limits. Irradiation and high-pressure processing are newer options. Every method trades off convenience, cost, and sensory quality, and most preserved foods combine several “hurdles” to keep microbes in check.