What is e-fold?

E-fold refers to the process of exponential growth or expansion, typically used to describe the growth rate of inflation, population, or technology. In finance, e-fold is used to measure the time it takes for an investment to increase or decrease by a factor of e or approximately 2.718. A 1 e-fold increase is equivalent to a growth rate of approximately 172.8% (100% plus the e-fold increase of 72.8%). The e-fold growth rate is commonly used in scientific and statistical analyses to describe the magnitude of change over time and to make predictions about future trends.