cdnjs is a free distributed JS library delivery service.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
Particles.js is a JavaScript library for creating particles.
PHP is a general-purpose scripting language used for web development.
Ubuntu is a free and open-source operating system on Linux for the enterprise server, desktop, cloud, and IoT.