* All the communications between the instances are signed with [Linked Data Signatures](https://w3c-dvcg.github.io/ld-signatures/) with the private key of the account that made the action
* We use the [ActivityPub](https://www.w3.org/TR/activitypub/) protocol (only server-server for now). Object models could be found in [shared/models/activitypub directory](https://github.com/Chocobozzz/PeerTube/tree/develop/shared/models/activitypub).
* All the requests are retried several times if they fail
* An instance has a websocket tracker which is responsible for all the video uploaded in it
* An instance has an administrator that can follow other instances
* An instance can be configured to follow back automatically
* An instance can blacklist other instances (only used in "follow back" mode)
* An instance cannot choose which other instance follow it, but it can decide to **reject all** followers
* After having uploaded a video, the instance seeds it (WebSeed protocol)
* If a user wants to watch a video, he asks its instance the magnet URI and the frontend adds the torrent (with WebTorrent), creates the HTML5 video player and streams the file into it
* A user watching a video seeds it too (BitTorrent) so another user who is watching the same video can get the data from the origin server and the user 1 (etc)