A doppelgänger is someone who looks almost exactly like another person but isn't related to them. The word comes from German and literally means “double walker.”

Imagine walking into a new classroom and seeing someone who could be your twin: same hair color, similar face shape, even the same expressions. That person would be your doppelgänger. Sometimes people discover their doppelgängers by accident when strangers approach them, convinced they know them from somewhere else.

Throughout history, doppelgängers have fascinated people. Some cultures believed that seeing your own doppelgänger was an omen or sign of bad luck, though there's nothing supernatural about two people simply looking alike. With billions of people in the world, it's not surprising that unrelated people sometimes share striking similarities.

Today, people sometimes use the word more loosely to describe anyone who strongly resembles someone else, like when friends joke that a celebrity is your doppelgänger. The internet has made finding doppelgängers easier: museums have created apps that match your selfie to portraits of historical figures, and social media has helped unrelated look-alikes discover each other across continents. Meeting your doppelgänger can be startling, amusing, or just plain weird, but it's also a reminder of how human features can combine in surprisingly similar ways.