What is Matrix? According to Wikipedia, Matrix “is an open standard and communication protocol for real-time communication”. Matrix should be feel familar for users of IRC, one of the first Internet communication protocols.

Like many modern social platforms, Matrix generally exists as multiple “federated” servers such that an account on one server allows access to many other servers. The SDF Matrix server – matrix.sdf.org – is a bit different: although rooms ¹⁾ on remote servers are still accessible, for various reasons login accounts are restricted to SDF members.

Unlike other SDF social platforms, Matrix accounts are by invitation only; to get an invite send an email to membership@sdf.org requesting a Matrix account along with the SDF username you plan to log in with. Most requests are processed within 48 hours; an email containing your Matrix login and password will be sent to the email address associated with your SDF username.

There are several Matrix clients ³⁾ for various platforms available; see https://matrix.org for specifics. An easy way to get started is to point your web browser at https://element.io/#/login, a browser-based Matrix client that is free to use. The default “Homeserver” is matrix.org; you will need to click “edit” and change this to matrix.sdf.org, then enter your login credentials and click “Sign in”. Once you've successfully signed in you'll likely be prompted to create a secondary passphrase which will be used to create encryption keys for your account. Subsequent logins will then prompt for either the passphrase or the security key.

Once you've setup up your account – you can change your display name, avatar, themes, media options, etc. via the “Settings” menu – please join the lobby and say hi! Posts in Matrix offer many formatting options as well as editting should the need arise.

Matrix often shares “space” via “bridges” with other protocol such as IRC and Jabbr; for example one can use the “Search” feature to search for public channels on libera.chat, a popular IRC server used by various free software projects. Most public room/channel names begin with a “#”, an IRC convention. Similarly, one can search for other users via the “People” tab. Matrix users are indicated with a “@” prefix, ie. “@someone:matrix.sdf.org”. Clicking on someone in the “People” listing will initiate a private chat with that person. If you aren't finding just the right room you can create one; click on the “+” under the “Home” icon to create a new “space”. Spaces can be public or private.

https://matrix.sdf.org displays some rudamentary ^{4) 5)} Matrix stats: local and remote rooms, total number of rooms, users and instances.
Synapse is running displays the SDF Matrix Synapse server status, when running.

1. More Features of Matrix
2. CommonMark
   1. CommonMark Spec