Focus on your most important email
Once activated you'll see two new tabs at the top of your inbox called Focused and Other. Your most important messages appear under Focused and the rest are moved to Other. You'll be informed about email flowing to Other, and you can switch between tabs any time to take a quick look.
No need to check the Clutter folder
Messages won't be moved to the Clutter folder anymore. Instead, email that would have been moved to Clutter will now go to Other. This makes it easier for you to stay on top of incoming email without leaving your inbox.
The more you use it, the better it gets
You can train Focused Inbox to be more accurate by moving email between Focused and Other. To do this, right-click a message and select "Move to Other" or "Move to Focused."