ClustrMaps widget is a visitor tracker, designed for general web and blog use.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
OpenResty is a web platform based on nginx which can run Lua scripts using its LuaJIT engine.
ShareThis provides free engagement and growth tools (e.g., share buttons, follow buttons, and reaction buttons) for site owners.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.