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.
Quick Answer. Thomas Edison is famous because he is the most prolific inventor in American history. His 1,093 patents, a record number, covered innovations and improvements in a number of areas such as electric power, motion pictures and sound recording. Edison was born in Ohio in 1847 and began experimenting at a young age.