Focused Inbox is a refinement and improvement of a previous feature called Clutter. Clutter’s purpose was also to help you focus on the most important items in your inbox, but it did so by moving “Other” email to a separate folder. Focused Inbox makes it easier for you to stay on top of incoming email without having to visit another folder.
Active Clutter users will receive the Focused Inbox, but it will be off by default and able to be turned on in Settings. If the users chooses to enable, they will no longer receive less important email in the Clutter folder. Instead, email will be split between the Focused and Other tabs in their inbox. The same machine-learned algorithm that moved items to the Clutter folder now powers Focused Inbox, meaning that any emails that were set to move to Clutter will now be moved to Other.
Turn Focus Inbox on/off
Read the help article for more details on the prompts users will see and how to turn Focused Inbox on and off: