Sterilization is the process of making something completely free from germs, bacteria, and other microorganisms that could cause disease or infection. When doctors sterilize their surgical tools before an operation, they use extreme heat or special chemicals to kill every last microbe. When you get a shot at the doctor's office, the nurse opens a sterile needle from a sealed package, ensuring nothing harmful can enter your body.

Hospitals sterilize everything from bandages to operating rooms. Scientists sterilize their laboratory equipment so germs won't contaminate their experiments. Even the cafeteria worker sterilizes kitchen surfaces to keep food safe.

Sterilization is more thorough than regular cleaning. Wiping down a counter removes visible dirt, but sterilizing it kills microscopic organisms you can't even see. The discovery of sterilization revolutionized medicine in the 1800s. Before doctors understood the importance of sterile conditions, many patients died from infections after surgery. Once hospitals began sterilizing their instruments and rooms, survival rates improved dramatically.