Author: Mary Sun, College student writer

Believe it or not, you have billions of bacterial cells on your body right now. Don't be alarmed, though, because almost all of these bacterial cells aren't going to make you sick. Just like everything, there are good and bad bacteria.

Bacteria that make you sick (like when you get strep throat, an ear infection or pneumonia) are called pathogenic bacteria. The best way to keep from getting sick from pathogenic bacteria is to be clean (see article on hygiene).

Washing your hands after using the restroom and before eating is important in preventing the bacteria from entering your body. If you get sick with a bacterial infection, the doctor will most likely prescribe some antibiotics that will kill the bad bacteria. Your doctor will tell you it is important to take all of your medication because you want to make sure every single bacteria cell is killed, otherwise your infection might come back.

Bacteria are very good at multiplying. They can grow from one bacterial cell to a million in a day! Bacteria are also very old. They have been living on our planet for millions of years, long before the dinosaurs! They are so good at adapting to different environments that they can live in places where the temperature is higher than the boiling point of water or lower than the freezing point of water. And they can change their DNA (genetic information) randomly.

Even though bacteria are very tiny organisms, they play very important roles in our lives. Good things that bacteria do include making yogurt, decomposing leaves into soil and helping us by making vitamins that our bodies can absorb.