A disinfectant is a chemical substance used to kill germs and bacteria on surfaces and objects. When you clean a kitchen counter with a spray containing bleach or another powerful cleaner, you're using a disinfectant to destroy tiny organisms that might make people sick.

Disinfectants work differently than regular soap and water. Soap helps wash germs away, but disinfectants actually kill them. Hospitals use strong disinfectants constantly to keep operating rooms safe. At home, people use disinfectants on bathroom fixtures, doorknobs, and cutting boards where raw meat was prepared.

Scientists developed the first effective disinfectants in the mid-1800s, which revolutionized medicine by dramatically reducing infections during surgery and childbirth.

You might also hear the verb form: to disinfect means to clean something with a disinfectant. A school nurse might disinfect the skin around a scraped knee before putting on a bandage. Some disinfectants are too harsh for skin, though, which is why we use gentler antiseptics on cuts and scrapes.