add webrtc

internals.md

@@ -9,6 +9,7 @@ Technologies Discord uses to provide the service, gathered from
 [Flask]: http://flask.pocoo.org
 [Punt]: https://github.com/discordapp/punt
 [Loqui]: https://github.com/discordapp/punt
+[WebRTC]: https://webrtc.org/
 
 
 ## Storage:
@@ -50,6 +51,11 @@ Technologies Discord uses to provide the service, gathered from
      voice servers need to be direct connections, so they don't pass through CF.
 
 
+## General technologies
+ - [WebRTC] for voice and video. [Source](https://blog.discordapp.com/how-discord-handles-two-and-half-million-concurrent-voice-users-using-webrtc-ce01c3187429),
+    which also goes on more detail on how the voice server architecture
+
+
 ## Many other sources
  - [Description of a full outage where they had to reboot everything](https://status.discordapp.com/incidents/dj3l6lw926kl)
  - [`sessions` and `presence` clusters get rebooted due to a host error in a `guild` node](https://status.discordapp.com/incidents/ywdwttd6b0hg)