Facebook pixel is an analytics tool that allows you to measure the effectiveness of your advertising.
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.
NitroPack creates optimised HTML cache for fast page loading experience.
Open Graph is a protocol that is used to integrate any web page into the social graph.
WP Engine is a website hosting provider.