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 born on February 11, 1947 in Milan, Ohio. Thomas Edison was the seventh and last child of Samuel Ogden Edison, Jr. and Nancy Matthews Elliott.