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 Edisonâs Early Life. Thomas Alva Edison was born on February 11, 1847, in Milan, Ohio. He was the seventh and last child born to Samuel Edison Jr. and Nancy Elliott Edison, and would be one of four to survive to adulthood.n his 84 years, Thomas Edison acquired a record number of 1,093 patents (singly or jointly) and was the driving force behind such innovations as the phonograph, the incandescent light bulb and one of the earliest motion picture cameras.