HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Query Migrate is a javascript library that allows you to preserve the compatibility of your jQuery code developed for versions of jQuery older than 1.9.
jQuery is a JavaScript library which is a free, open-source software designed to simplify HTML DOM tree traversal and manipulation, as well as event handling, CSS animation, and Ajax.
Priority Hints exposes a mechanism for developers to signal a relative priority for browsers to consider when fetching resources.
Twenty Seventeen is the default WordPress theme for 2017.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.