Apache Traffic Server is an open-source caching and proxying server that serves as an HTTP/1.1 and HTTP/2 reverse proxy with caching capabilities, load balancing, request routing, SSL termination, and support for advanced HTTP features.
Open Graph is a protocol that is used to integrate any web page into the social graph.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.