Gmail is rolling out a new feature for the inbox. They announced it in a May 2013 blog entry.
We get a lot of different types of email: messages from friends,
social notifications, deals and offers, confirmations and receipts,
and more. All of these emails can compete for our attention and make
it harder to focus on the things we need to get done. Sometimes it
feels like our inboxes are controlling us, rather than the other way
around.
The big things is that the inbox now has Tabs
As of now you only have five tabs available:
Primary: Messages from friends and family and other messages that don’t appear in other tabs
Promotions: Deals, offers, and promotional emails
Social: Emails from social networks, media-sharing sites, online dating services, gaming sites, and other social websites
Updates: Notifications, confirmation emails, receipts, bills, and online statements
Forums: Email groups, discussion boards, and mailing lists