WHY? is our attempt to answer all the questions every little kid asks. Have a question? Send it to why@mentalfloss.com.Boogers are a sign that your nose is working properly! The snot in your nose is called mucus (MYOO-cuss), but it's much more fun to call it boogers. Mucus is made up of 95 percent water, 3 percent mucin (that's what makes it slimy), and 2 percent other things, like proteins and salt. That's why snot can taste salty. But don't eat your boogers!

Your nose makes up to a quart of mucus each day—enough to fill a small ice cream container! Some days it will be more runny, like when you have a cold. When you are sick, your body makes more mucus to help keep you from getting even sicker. Those days, you might have to keep wiping your nose with a tissue. But other days the mucus stays in your nose and hardens into real boogers.

Mucus is there to protect your nose and your lungs. This slimy stuff keeps the inside of your noise moist so it doesn't dry out. It also traps the dirt, dust, and germs that you breathe in. That way they won't go all the way into your body and cause an infection or make it hard to breathe. Snot also has ingredients that fight off infection, like antibodies (AN-tee-bod-ees) and white blood cells. As the mucus catches dirt or germs, it will either turn hard or get really goopy as your nose tries to flush the bad stuff out of your body.

Sometimes your boogers are weird colors, like white, yellow, or green. Those colors can be caused by the things that can make you sick, like bacteria or a virus, or by the white blood cells fighting them off. So just think of your boogers as part of a slimy shield protecting you. Make sure to leave them in your nose until you find a tissue and a trash can where you can throw away all the germs the boogers collected.

To learn more about boogers and mucus, watch this video from Brit Lab.