How the url parameters are mapped to params hash?

Hi,
   I have created the url
"http://localhost:3000/groups/home?group_id=1&parent_id=3".
  I have one method in which I am able to access the url parameters by
using params[:group_id] and params[:parent_id].
My question is that how the params hash is get created? and who creats
this hash?

Thanks,
Tushar

Hi,
  I have created the url
"http://localhost:3000/groups/home?group_id=1&parent_id=3".
I have one method in which I am able to access the url parameters by
using params[:group_id] and params[:parent_id].
My question is that how the params hash is get created? and who creats
this hash?

ActionController creates it for you (grungy details in request.rb)

Fred