The natural logarithm is the logarithm based on the natural constant e (approximately equal to 2.7 18). The base of natural logarithm is e, which is an irrational number. It appears in many fields of mathematics, including probability theory, calculus and statistics.

The basic property of natural logarithm is that if the natural logarithm of a number is x, then the value of this number is the x power of e, for example, ln(y)=3, then y = the third power of e =20.086.

In mathematical modeling, natural logarithm can be used to represent the derivative of exponential function or the parameters of logarithmic function. Natural logarithm can also be used to indicate logarithmic growth or logarithmic decay.