If you're feeling crummy, it's probably because nasty bacteria or some other germs have gotten into your
body and made you sick. Bacteria are so tiny that you can't see them with just your
eyes, but there are thousands, millions, even billions of them all over you, inside
and out! This might sound kind of gross, but lots of bacteria actually help our bodies.
The good bacteria are good for us, and the bad bacteria can make us sick. They may
be to blame for your next sore throat or ear