Rules are IF/THEN statements that you can use to automate your inbox triage.
For example:
IF channel_type is (DM or Goup DM)
THEN move to Important inbox
Find them in the bottom-left of your sidebar
Keep in mind that rules are evaluated in order.
Every channel has a Default Inbox where messages from that channel will go.
You can also bulk update Default Inboxes from the Rules page.
Here's what the rule does:
IF the message includes an @mention
THEN move that to your Important inbox, and notify you.
Learn more about Rules here.
In the bottom-left, click this icon to open the Rules page. Here you can bulk update which #channel messages appear in which inboxes.
Every channel has a Default Inbox where messages from that channel will go.
Learn more about Default Inbox Settings