Exponential functions were created by two men, John Napier and Joost Burgi, independently of each other. Napier was from Scotland, and his work was published in 1614, while Burgi, a native of Switzerland, developed his work in 1620.
Although Napier and Burgi are generally credited with the invention of exponential functions, what they actually created is quite different from modern exponential functions. Also known as logarithms, exponential functions are used in many different disciplines, from astronomy to chemistry. Napier developed his logarithm theory based upon algebra, while Burgi developed his based on geometry. The commonly known exponential function is defined as a base number with a raised exponent, also known as a "power."