urbit/pub/doc/talk/help.txt

Besides `;help`, there are four main `talk` commands:

    ;join ~urbit-name/channel

`;join` subscribes your main feed to a remote channel.

    ;create channel %name 'description'

`;create` creates a channel on your urbit.

    ;<number>

`;<number>` activates a previous message number, like a URL that got
clipped.

    ;<target>

`;<target>` sets the target for your messages, such as `;~urbit-name`
for a private message, or `;/channel`

    ;
    
By itself is "autotarget", and maintains the audience of the last message
heard.