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 died of complications of diabetes on October 18, 1931, in his home, Glenmont, in West Orange, New Jersey. He was 84 years old. Many communities and corporations throughout the world dimmed their lights or briefly turned off their electrical power to commemorate his passing.