how to stretch the grid spacing at the edges of the computa

please could any one explain to me how to stretch the grid
spacing at the edges of the computation window for finite-difference calculations. I know that this is useful when you would like to increase the size of the computation window without increasing the total number of points in the computational domain.

I know that there is four different expansion
methods: uniform, linear, parabolic and geometric. what is the difference betwen them?

could any one suggest sources for this issue?

Regards