Inbox is a roll-up of notifications across all of your teams and projects. It is designed to help you triage unread notifications quickly and easily. It is located above your list of Teams on both desktop and mobile devices.
After opening your Inbox, you'll see a 'toggle dot' above your list of notifications. This toggle dot lets you switch between two ways of viewing all of your notifications in one place.
When the dot is faded, you're seeing your most recent messages. When the dot is fully black, you're seeing only unread messages.
To clear a red dot in Inbox, simply click or tap it. If you'd like to mark a notification as unread, simply click the empty circle to restore the unread status.