What does force_ssl do in Rails?

Question

In a previous question I found out that I should be setting nginx ssl termination and not having Rails process encrypted data.

Then why does the following exist?

Answer 1

This setting forces HTTPS by redirecting HTTP requests to their HTTPS counterparts. So a browser visiting http://domain.com/path will be redirected to https://domain.com/path.

Leaving the setting commented out would allow both protocols.

You still have to configure your web server to handle HTTPS requests.