Screenshot of the YouTube app: Below a video about a package for Emacs, YouTube puts an image of a missile. The header above the image says "Key Concepts". Below the image, YouTube says that "A projectile is an object that is propelled by the application".
https://cdn.fosstodon.org/media_attachments/files/114/743/989/236/099/754/original/1dbd58f2845ae29a.png