HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Open Graph is a protocol that is used to integrate any web page into the social graph.
SoundCloud widget gives you the ability to upload, manage and share tracks.
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.