Cloudflare is a web-infrastructure and website-security company, providing content-delivery-network services, DDoS mitigation, Internet security, and distributed domain-name-server services.

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.

YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.

Popper is a positioning engine, its purpose is to calculate the position of an element to make it possible to position it near a given reference element.