A doorbell is a device that makes a sound to let people inside a house or building know that someone is at the door. When you press the button outside, it triggers a chime, buzz, or melody inside so someone can come answer the door.

Before doorbells, visitors had to knock loudly or use a heavy metal door knocker. The electric doorbell was invented in the 1830s and became common in homes by the early 1900s. Today, some doorbells are simple buzzers, while others play musical tunes. Modern “smart” doorbells include cameras that let homeowners see who's at the door through their phone, even when they're not home.

The moment you hear a doorbell ring, it creates a sense of anticipation: Who could it be? A package delivery? A friend stopping by? That simple ding-dong sound has become so familiar that we instantly recognize what it means, even in movies or TV shows.