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 Alva Edison Was Born in 1847 Early Years Year Invention Description 1863 Automatic Telegraph Repeater Edison's first invention at 16.It sent telegraph signals between unmanned stations, allowing almost anyone to easily and precisely translate code at his own speed and convenience.dison patented a system for electricity distribution in 1880 (U.S patent 239,147), which was essential to capitalize on the invention of the electric lamp. On December 17, 1880, Edison founded the Edison Illuminating Company.