Project vs Application in Django

One project can contain many applications. An application can be reused in another project.

The Difference

Project — the entire site configuration: settings.py, the main urls.py, wsgi.py.

Application — a modular component with a specific purpose: models, views, urls, templates.

mysite/              ← PROJECT
├── manage.py
├── mysite/
│   ├── settings.py
│   └── urls.py
├── blog/            ← APPLICATION
│   ├── models.py
│   └── views.py
└── shop/            ← APPLICATION
    ├── models.py
    └── views.py

One project can contain many applications. An application can be reused in another project.

Creating an Application

python manage.py startapp tasks

INSTALLED_APPS — Registration

Every application must be listed in INSTALLED_APPS; otherwise Django will not recognize it:

# settings.py
INSTALLED_APPS = [
    # Built-in Django applications
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',

    # Third-party
    'rest_framework',
    'crispy_forms',

    # Your applications
    'tasks',
    'blog',
    'shop',
]

AppConfig — Application Configuration

# tasks/apps.py
from django.apps import AppConfig

class TasksConfig(AppConfig):
    default_auto_field = 'django.db.models.BigAutoField'
    name = 'tasks'
    verbose_name = 'Tasks'

You can explicitly reference it in INSTALLED_APPS:

INSTALLED_APPS = [
    'tasks.apps.TasksConfig',  # instead of just 'tasks'
]

When to Extract a Separate Application

• Users and authentication → accounts
• Blog with articles → blog
• Cart and orders → shop
• API → api

Rule of thumb: if the functionality can be described with a single noun, it is a candidate for a separate application.