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, in full Thomas Alva Edison, (born February 11, 1847, Milan, Ohio, U.S.âdied October 18, 1931, West Orange, New Jersey), American inventor who, singly or jointly, held a world record 1,093 patents. In addition, he created the worldâs first industrial research laboratory.