Clarified 404.html usage, excplicitly stated that it's used when DEBUG is False

            raise Http404("Poll does not exist")

        return render_to_response('polls/detail.html', {'poll': p})

In order to use the ``Http404`` exception to its fullest, you should create a

template that is displayed when a 404 error is raised. This template should be

called ``404.html`` and located in the top level of your template tree.

If you provide a message when raising an ``Http404`` exception, it will appear

in the standard 404 template displayed when :setting:`DEBUG` is ``True``. Use

these messages for debugging purposes; they generally aren't suitable for use

in a production 404 template.

In order to show customized HTML when Django returns a 404, you can create an

HTML template named ``404.html`` and place it in the top level of your

template tree. This template will then be served when :setting:`DEBUG` is set

to ``False``.

When :setting:`DEBUG` is ``True``, you can provide a message to ``Http404`` and

it will appear in the standard 404 debug template. Use these messages for

debugging purposes; they generally aren't suitable for use in a production 404

template.

.. _customizing-error-views: