It is a non-linear systems. It is an opposite of a linear system.
But in a non linear system, the previous state of the system feeds back into the current state of the system, thus enabling the current ratio between the input and the output to be greater or less than its previous ratio.
It is counter intuitive. Here rate of growth itself is growing.
This phenomenon is captured within mathematical notation - Exponential. Exponential is also called Powers.
Power law - One quantity varies as a power of another.
Ex: the volume of a cube.
If the side is of length 5cm, the volume is 5^3 = 125cm3. If the side is 6cm, the volume is 6^3 = 216cm3
91cm3 increase.
Just by increasing 1cm on each side, we get increase in 91cm3 of the volume.
If it is a linear system of f(x) = 2x. Then the increase would be 2x6 - 2x5 = 12 - 10 = 2. Just 2.
91 vs 2 is the difference between the linear system and the non-linear system.
This is related to network effect