An earworm is a catchy song or melody that gets stuck in your head and plays over and over, whether you want it to or not. The term comes from the way these tunes seem to burrow into your brain like a little worm, refusing to leave.

You know the feeling: you hear a song on the radio in the morning, and hours later you're still humming it during math class, at lunch, and while brushing your teeth before bed. Sometimes you don't even like the song that much, but your brain keeps replaying it anyway. Jingles from commercials are especially good at becoming earworms because they're designed to be memorable and repetitive.

Scientists who study how our brains process music have found that earworms tend to have certain features: a catchy rhythm, simple melodies, and unexpected twists that make them interesting without being too complicated. Songs with lyrics that repeat a lot are particularly good at becoming earworms.

The funny thing about earworms is that trying not to think about them can make them worse. Some people find that listening to the whole song all the way through can help get it out of their head, while others prefer to replace it with a different tune. Either way, earworms are a perfectly normal quirk of how our musical memory works.