HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Mod_perl is an optional module for the Apache HTTP server. It embeds a Perl interpreter into the Apache server. In addition to allowing Apache modules to be written in the Perl programming language, it allows the Apache web server to be dynamically configured by Perl programs.
Perl is a family of two high-level, general-purpose, interpreted, dynamic programming languages.
PHP is a general-purpose scripting language used for web development.
WordPress is a free and open-source content management system written in PHP and paired with a MySQL or MariaDB database. Features include a plugin architecture and a template system.