“e”
The mathematical constant denoted e is the base of the natural logarithm which has value of approximately 2.718.
Exponential Function
The exponential function is the function consisting of the base of the natural logarithm e taken to the power of a given variable.
Logarithm
The logarithm is the power to which a number (called the base) must be raised to produce a given number. For example, the logarithm of 100 with respect to the base 10 is 2.
Natural Logarithm
The natural logarithm is the logarithm having base e.