Step-by-step guide to scaling a Flask app: create a virtualenv, install Flask and Gunicorn, write a basic app, then run it via gunicorn -w 4 --bind unix:/tmp/myapp.sock myapp:app to use multiple workers and a Unix socket; for production, put Gunicorn (or uWSGI) behind Nginx, proxying to /tmp/myapp.sock, enable the site, and reload Nginx for a robust, production-ready deployment.