The Mandela Effect is a phenomenon where a large group of people remember an event, fact, or detail differently from how it actually occurred. The term was coined by Fiona Broome in 2009 after she discovered that she and many others incorrectly remembered Nelson Mandela dying in the 1980s while he was actually alive until 2013. This discrepancy led her to believe that these shared false memories might indicate alternate realities, time travel, or parallel universes intersecting.