Google Analytics is a free web analytics service that tracks and reports website traffic.
JSDelivr is a free public CDN for open-source projects. It can serve web files directly from the npm registry and GitHub repositories without any configuration.
Open Graph is a protocol that is used to integrate any web page into the social graph.
OpenResty is a web platform based on nginx which can run Lua scripts using its LuaJIT engine.
Twitter is a 'microblogging' system that allows you to send and receive short posts called tweets.