use of custom routings

what is the main use of
1)map.resources
2)nested resources
3)if we use only
  map.connect ':controller/:action/:id'
  map.connect ':controller/:action/:id.:format'
in routes.rb ,then what is the drawback of that ?

can any one ?

what is the main use of
1)map.resources
2)nested resources
3)if we use only
map.connect ':controller/:action/:id'
map.connect ':controller/:action/:id.:format'
in routes.rb ,then what is the drawback of that ?

http://guides.rails.info/routing/routing_outside_in.html#_restful_routing_the_rails_default

Frederick Cheung wrote:

Frederick Cheung wrote:

what is the main use of

http://guides.rails.info/routing/routing_outside_in.html#_restful_routing_the_rails_default

i have confused a little about perfomance issue while using nested
routing
if i create a nested routes like this
#---------------in routes.rb-----------------------------------------
map.resources :countries do |country|
  country.resources :states do |state|
    state.resources :cities do |city|
      city.resources :streets, :has_many =>:wards
    end
  end
end