Have you ever eaten something that tasted a little funny and then felt sick a couple of hours later? Maybe you had diarrhea or you threw up. If so, it sounds like you're familiar with food poisoning. Food poisoning is caused by bacteria and, sometimes, viruses or other germs. They can get into the food we eat or the liquids we drink.
We can't taste, smell, or see these germs (at least not without a microscope). But even though they're tiny, they can have a powerful effect on the body. In a few cases, food poisoning can be severe enough to require a visit to the doctor or hospital.