Germs live everywhere. You can find germs in the air, on food, plants and animals, in the soil, in the water, and on just about every other surface — including your own body.
Most germs won't harm you. Your immune system protects you against a multitude of infectious agents. However, some germs are formidable adversaries because they're constantly mutating to breach your immune system's defenses. Knowing more about how germs work can increase your chances of avoiding infection.