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.
jQuery CDN is a way to include jQuery in your website without actually downloading and keeping it your website's folder.
jQuery is a JavaScript library which is a free, open-source software designed to simplify HTML DOM tree traversal and manipulation, as well as event handling, CSS animation, and Ajax.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Tilda is a web design tool.
Unpkg is a content delivery network for everything on npm.
VK is a Russian online social media and social networking service.