What are boogers?  Browse → Science → Stinky, Yucky, Icky
Boogers are a pretty good pick! The reason you have them is
because you have mucus, or “snot,” which is the squishy, slimy,
slippery stuff made in your nose that you might also feel at the
back of your throat sometimes.   The purpose of mucus is to
protect your lungs from harmful things like dust and dirt that
are naturally in the air when you breathe. The gooey mucus
catches these things so they can’t get all the way down to your
lungs! Mucus also helps keep your respiratory (breathing) system
warm and moist. Most of the mucus your body makes just drains
into your throat unnoticed, even though you produce about a
quart of it every day!  Eventually, little bits of the mucus
inside your nose will get dry and bunch together, leaving you
with a booger! See… it’s really SNOT that hard to understand!
by   (whyzz writer)