Django HttpResponseRedirect

All of the responses are correct but a better approach is to give names to your URLs in urls.py and hint to them in views with reverse function (instead of hard coding URL in views).

urls.py:

(r'^contact/$', contact, name='contact'),
(r'^contact/thanks/$', contact_thanks, name='thanks'),

And hint them in views.py like this:

from django.urls import reverse

return HttpResponseRedirect(reverse('app_name:thanks'))

This is better for future approach and follow the DRY principle of Django.

It's not the POST button that should redirect, but the view.

If not differently specified, the form (the HTML form tag) POSTs to the same URL. If the form is on /contact/, it POSTs on /contact/ (with or without slash, it's the same).

It's in the view that you should redirect to thanks. From the doc:

def contact(request):
    if request.method == 'POST': # If the form has been submitted...
        form = ContactForm(request.POST) # A form bound to the POST data
        if form.is_valid(): # All validation rules pass
            # Process the data in form.cleaned_data
            # ...
            return HttpResponseRedirect('/thanks/') # Redirect after POST
    else:
        form = ContactForm() # An unbound form

    return render_to_response('contact.html', {
        'form': form,
    })

Change /thanks/ to /contact/thanks/ and you're done.