Sterilization (or sterilisation) is the elimination of all transmissible agents (such as bacteria, prions and viruses) from a surface, a piece of equipment, food or biological culture medium. This is different from disinfection, where only (comparatively larger) microorganisms are removed by a disinfectant. The first application of sterilization was the partial heat sterilization of food and water. Tools (e.g. super-heated rocks and skewers) and methods to carry out partial heat sterilization of food were probably invented and reinvented soon after the discovery of fire. Cultures that practice heat sterilization of food and water have longer life expectancy and lower rates of disability. Ingestion by children of contaminated food and water remains a leading cause of death and disability in the developing world.

Heat sterilization is known to have been in used in Ancient Rome, but it mostly disappeared throughout the Middle Ages resulting in significant increases in disability and death from surgical procedures.
Sterilization can be achieved through heat, chemicals, radiation, or filtration.