I What is the significance of slow-roll inflation in cosmology?

[AHSAN MUJTABA]

I have recently studied the slow-roll inflation model. In it, slow-roll inflationary conditions are mentioned in a lot of places(these conditions needed to be satisfied for inflation to happen). I don't really understand the meaning and purpose of slow-roll inflation. I want to know a very simple explanation regarding this. The slow roll parameter($\epsilon_{H}$) is given by:
$\epsilon_{H}=\frac{\dot{H}}{H}$. For inflation to happen, $0<\epsilon_{H}>1$.
Can somebody help me with a simple story-like explanation? What exactly is going on here?
$H$ is Hubble's parameter in the equation.

 

[AHSAN MUJTABA]

Sorry, the slow-roll parameter is: $\epsilon_{H}=\frac{\dot{H}}{H^{2}}$.