The base app is used as a base template for all of your apps

1. Add "base" to your INSTALLED_APPS setting like this:

   INSTALLED_APPS = (
   ...
   'base',
   )

2. Include the inventory URLconf in your project urls.py like this:
   from django.views.generic import TemplateView
url(r'^$', TemplateView.as_view(template_name="base/index.html"), name='home'),

In your apps html template
{% extends 'base/base.html' %}
{% block title %} App title here {% endblock %}
{% block content %} app content {% endblock %}