An impostor is someone who pretends to be someone else in order to deceive people. An impostor might claim to be a doctor without any medical training, or pretend to be a school official to gain access to a building. The key is that they're deliberately trying to trick others into believing they're someone they're not.

Throughout history, famous impostors have fooled entire communities. Some pretended to be royalty, others claimed to be war heroes or experts in fields they knew nothing about. In the 1800s, a man named Arthur Orton tried to claim he was a wealthy heir who had been lost at sea, even though the real heir's mother eventually realized he was lying.

People sometimes experience something called impostor syndrome, where they feel like frauds even when they've genuinely earned their success. A talented student might worry they don't deserve their good grades, or a skilled musician might fear being “found out” as untalented. That's different from being an actual impostor, because those people really did earn their accomplishments.