How to Run Sites Securely with Apache and Php-fpm on Ubuntu 16.04 LTS

A great security feature of Php FastCGI Process Manager (Php-fpm) is its ability to run Php scripts with different users. This in addition to its other merits such as performance and many fine grained options for tuning makes it the best choice for running Php sites. Before anything else, I must admit that Nginx with Php-fpm is preferred than Apache with Php-fpm for performance reasons mostly. There are fine articles such as this one explaining how to accomplish exactly the same as the current topic with Nginx and not with Apache. The setup for Php-fpm with Apache is similar but there are some Apache specifics which are important and on which the current article stresses.