DEFINITION of 'Purchasing Power Parity-PPP'. An economic theory that estimates the amount of adjustment needed on the exchange rate between countries in order for the exchange to be equivalent to each currency's purchasing power.
Thomas Edison's most famous invention, the lightbulb, paved the way for modern life.
Thomas Edison is famous for his lightbulb, but he never won a Nobel Prize. Announced Monday, the award kicks off the annual salute to human accomplishment that is Nobel week, including Friday's announcement of the Nobel Peace Prize.