Archkre,
I do not mean to offend u, but are you here on this forum strictly to ask questions, or to also help LEGAL immigrants like us at all?
Like techy mentioned, havent u done any research at all in this department? It has been one whole year now, since Retrogression started, and NOW u are asking what retrogression is and how it started? A simple search on google "Green Card Retrogression" or "EB3 retrogression" will give you plenty of results.
Once again i dont mean to offend u in any way, but if you want to help us and help yourself, you are going to have to come up to speed with current information.