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.
Polyfill is a service which accepts a request for a set of browser features and returns only the polyfills that are needed by the requesting browser.
ProcessWire is an open source content management system (CMS) and framework (CMF).
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.