Bootstrap is a free and open-source CSS framework directed at responsive, mobile-first front-end web development. It contains CSS and JavaScript-based design templates for typography, forms, buttons, navigation, and other interface components.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Lightbox is small javascript library used to overlay images on top of the current page.
Varnish is a reverse caching proxy.