Mumps is a contagious viral disease that causes painful swelling of the salivary glands, especially the ones just below and in front of your ears. When someone has mumps, their face puffs out on one or both sides, making their cheeks look swollen like a chipmunk storing nuts. The swelling usually hurts, especially when chewing or swallowing, and people with mumps often run a fever and feel generally miserable.

Before vaccines became common in the 1960s, mumps was something almost every child caught at some point. Entire classrooms would come down with it, one student after another. Today, most children receive the MMR vaccine (which protects against measles, mumps, and rubella), making the disease much rarer. When mumps does occur, it spreads through coughing, sneezing, or sharing drinks, similar to how a cold spreads.

The word mumps comes from an old term meaning “to grimace” or “to be sulky,” probably because the swelling and pain can make people look grumpy and want to mope around. While mumps is usually uncomfortable and goes away on its own after a week or two, it can occasionally cause more serious problems, which is why vaccination is so important.