What is e (2.718…) and why does it literally appear everywhere?

Question

What is e (2.718…) and why does it literally appear everywhere?

In: 756

Answer 1

e is the number that solves the property that e^x is the derivative of e^x . As suggested in another comment, the derivative of 2^x is less than 2^x while the derivative of 3^x is more than 3^x.