Get list of categories ,subcategories and sub-subcategories in custom script

This tutorial is going to show you one of the ways to list all sub-categories and sub sub categories through custom script for your Magento store.In This script I have shown all subcategories on the basis of main category means Root Catalog's Id.
If you change the $id = 1 then it will display suabcategory upto the first level that looks like below.