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.
PayPal is an online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like checks and money orders.
Twitter is a 'microblogging' system that allows you to send and receive short posts called tweets.