cdnjs is a free distributed JS library delivery service.
Craft CMS is a content management system for building bespoke websites.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Imgix is a visual media platform for managing, processing, rendering, optimising and delivering your existing images.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
Open Graph is a protocol that is used to integrate any web page into the social graph.
SEOmatic facilitates modern SEO best practices & implementation for Craft CMS 3.