Sterilization is the treatment that destroys, removes, or inactivates all forms of microbial life, including resistant bacterial spores. It is the highest level of microbial control, when properly performed.
Sterilization can use several methods, including pressurized steam in an autoclave, dry heat, chemical sterilants, filtration, and ionizing radiation. The appropriate method depends on the material being treated and whether it can tolerate heat, moisture, or chemicals.
The key distinction is that disinfection reduces or destroys many pathogens but may leave bacterial spores behind. Pasteurization uses controlled heat to reduce harmful microbes and slow spoilage; it is not intended to make a product sterile. Antisepsis applies antimicrobial treatment to living tissue, such as skin.
Sterility is especially important for surgical instruments, injectable medicines, laboratory media, and devices that enter sterile body sites. Even sterilized objects must be protected from recontamination after treatment.