Apache is a free and open-source cross-platform web server software.
Contao is an open source CMS that allows you to create websites and scalable web applications.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
PHP is a general-purpose scripting language used for web development.
Polyfill is a service which accepts a request for a set of browser features and returns only the polyfills that are needed by the requesting browser.