New files
templates/registration/login.html
{% extends "app/base.html" %}
{% block content %}
  <h1>Log in</h1>
  <form method="POST">
    {% csrf_token %}
    {{ form.as_p }}
    <button type="submit">Log in</button>
  </form>
{% endblock content %}
Modified files
djangocourse/settings.py
--- 
+++ 
@@ -119,6 +119,9 @@
 ]
+LOGIN_REDIRECT_URL = "home"
+LOGOUT_REDIRECT_URL = "login"
+
 # Internationalization
 # https://docs.djangoproject.com/en/5.1/topics/i18n/
djangocourse/urls.py
--- 
+++ 
@@ -20,5 +20,6 @@
 urlpatterns = [
     path("admin/", admin.site.urls),
     path("articles/", include("app.urls")),
+    path("accounts/", include("django.contrib.auth.urls")),
     path("__debug__/", include("debug_toolbar.urls"))
 ]
templates/app/base.html
                    --- 
+++ 
@@ -6,7 +6,21 @@
   <title>Djangocourse</title>
 </head>
 <body>
-  <nav>Common navigation bar for all templates</nav>
+  <nav>
+    <ul>
+      <li><a href="{% url 'home' %}">Articles</a></li>
+      <li>
+        {% if user.is_authenticated %}
+          <form method="POST" action="{% url 'logout' %}">
+            {% csrf_token %}
+            <button type="submit">Log out</button>
+          </form>
+        {% else %}
+          <a href="{% url 'login' %}">Log in</a>
+        {% endif %}
+      </li>
+    </ul>
+  </nav>
   {% block content %}
   {% endblock content %}