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.
Updated March 13, 2017. âThe legendary inventor Thomas Edison was the father of landmark inventions, including the phonograph, the modern light bulb, the electrical grid, and motion pictures. Here's a look at a few of his greatest hits. â. Thomas Edisonâs first great invention was the tin foil phonograph.