DoubleClick Ad Exchange is a real-time marketplace to buy and sell display advertising space.
Google AdSense is a program run by Google through which website publishers serve advertisements that are targeted to the site content and audience.
OpenResty is a web platform based on nginx which can run Lua scripts using its LuaJIT engine.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.