Google Analytics is a free web analytics service that tracks and reports website traffic.
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.
Spotify Widgets provide an embeddable view of a track, artist, album, user, playlist, podcast or episode for use within your web project.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.