Mucus is snot and other slime from inside your body. More specifically, mucus is a secretion of your body's mucus membranes that lubricates the inside of your body and helps protect you from bacteria. You’re welcome.
Even the history of the word mucus is gross — roots from Greek and Latin all mean “snot” and “slippery, slimy.” Mucus drips out of your nose and even slips down your throat when you’re sick. This happens because your membranes produce too much mucus when you’re sick. Mucus isn’t all bad though — your body uses it to help food go down your throat easier, and it keeps bacteria out. Mucus is gross, but germs are worse!