Focused Inbox Coming to Outlook on the Web, Outlook for Mac
Microsoft has announced that from April through June, the Focused Inbox feature already available in Outlook for iPhone and Android will begin appearing in Outlook on the Web (outlook.cornell.edu) and Outlook 2016 for Mac. The release date for this feature in Outlook for Windows 2016 is not yet available because the update that will contain it is still being worked on.
Focused Inbox attempts to bring the emails most important to you to the fore by separating your inbox into two tabs—Focused and Other. Your most important emails are on the Focused tab, while the rest remain easily accessible—but out of the way—on the Other tab. You’ll be informed about email flowing to Other, and you can switch between tabs at any time to take a quick look.
A video about the feature appears in Microsoft's blog post about Focused Inbox.
When Focused Inbox becomes available in a particular version of Outlook, the application will ask if it should be turned on (the default is for it to be off). It is intended as an improvement over a similar feature, Clutter. If the user chooses to turn Focused Inbox on, and their account has Clutter enabled, Clutter will be turned off across the account, including for clients that don't yet have Focused Inbox functionality. Individuals for whom consistency across email applications is important may want to wait to turn on Focused Inbox until it is available universally.
See Microsoft's support website for more details about how Focused Inbox works and answers to frequently asked questions.