Notifications: Shows a list of all spaces where you have notifications selected and something new happened.
Unread: Shows all unread messages.
People: Shows a list of all people you’ve collaborated with in order of the last contact.
Favorites: Shows a list of all spaces you marked as favorites by clicking the star on the top left corner of a space.
@mentions to me: Shows a list of all messages you have personally been @mentioned in.
@mentions to all: Shows a list of all messages where everyone was @mentioned in spaces you are a member of.
Flag: shows a list of all messages you’ve flagged. Every message can be flagged for action later by clicking its flag icon.