According to Flask's documentation:
You can use the builtin server during development, but you should use a full deployment option for production applications.
Assume I am using mod_wsgi.
Is Flask still running "under the hood" with Apache delegating to it or is Flask "gone"? According to this SO, one of Flask's obvious limitations is that it is single-threaded. If Apache is just delegating to Flask, wouldn't we run into the same issues? And if not, what is Flask for at all? What makes it a "Flask application"? In other words, is a production Flask application running under an Apache server really a Flask application and if so, why?