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.
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.
Twitter is a 'microblogging' system that allows you to send and receive short posts called tweets.