Nash Equilibrium
A state in a strategic game where no player can improve their outcome by changing strategy alone. Everyone is doing their best given what everyone else is doing — even if the collective result isn't optimal.
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Origin
Developed by mathematician John Forbes Nash Jr. in his 1950 paper at Princeton, when he was just 21. The concept became a cornerstone of game theory, applicable to economics, evolutionary biology, political science, and military strategy. Nash's life and work were depicted in the 2001 film "A Beautiful Mind." He shared the 1994 Nobel Prize in Economics.
Updated February 22, 2026