Matrix is an ambitious new ecosystem for open federated Instant Messaging and
VoIP. The basics you need to know to get up and running are:

  * Everything in Matrix happens in a room. Rooms are distributed and do not
    exist on any single server. Rooms can be located using convenience
    aliases like #matrix:matrix.org or #test:localhost:8448.
  * Matrix user IDs look like @matthew:matrix.org (although in the future you
    will normally refer to yourself and others using a 3PID: email address,
    phone number, etc rather than manipulating Matrix user IDs)

Synapse is an open-source Matrix homeserver written in Python/Twisted,
developed and maintained by the Matrix.org Foundation core team.