It may seem like your runny nose and phlegmy throat only exist to drive you crazy and ruin your life, but au contraire, according to this (surprisingly) adorable TED-Ed video. Mucus is always around to help fight infection, even when you're not sick. In fact, every person produces — prepare yourself — more than a liter of mucus a day. That's a lot of snot.
Think of mucus as your shiny, gooey protective armor: The wet surfaces of your body that aren't covered by skin — such as your eyes, mouth, lungs, and stomach — get a coating. And that mucus coating is a pro at multitasking, keeping tissues from drying out and cracking, trapping and removing things that could make you sick, and maintaining the body's bacteria to prevent illness.
So even though you probably associate the annoying dribble of mucus coming from your nose with being sick, it's actually helping you stay healthy. And because mucus is unique in its ability to lubricate, keep your body clean, fight infection, and domesticate a bacterial population, you might actually want to say thank you to the slimy little buggers — err, boogers? — next time you use a Kleenex.