title: Django - Forms - What does (?P<pk>\d+)/$ signify?
body: <p>I am new to django. I was creating forms in django with the help of an online tutorial. I didnot understand a line in the urls.py file. Can someone explain what exactly it means?</p>
  
  <pre><code>from django.conf.urls import url
  from . import views
  from . views import BlogListView, BlogDetailView, BlogCreateView
  
  urlpatterns = [
      url(r'^$', views.BlogListView.as_view(), name='post_list'),
      url(r'^post/(?P&lt;pk&gt;\d+)/$', BlogDetailView.as_view(), name='post-detail'),
      url(r'^post/new/$', BlogCreateView.as_view(), name='post_new'),
      url(r'^post/(?P&lt;pk&gt;\d+)/edit/$', BlogUpdateView.as_view(), name='post_edit'),
  ]
  </code></pre>
  
  <p>I did not understand the following line:</p>
  
  <pre><code>url(r'^post/(?P&lt;pk&gt;\d+)/$'
  </code></pre>
  
  <p>What does <code>(?P&lt;pk&gt;\d+)/$</code> signify?
  Help please</p>