There has been a major update of the Gmail UI of late, with a new Tabbed Inbox to have all our emails organised, thereby furnishing a more refined look. The feature is optional and can be enabled by clicking on Configure Inbox in the Settings tab.
At present five categories are available - Primary, Social, Promotions, Updates and Forums.The feature, which Google is still rolling out worldwide across all platforms, comes after Google's previous stints with Inbox organisation - Labels and Priority Inbox.
However, the feature has a few con-sides, like you may not get to instantly view new mails hitting your Inbox.You have to check all 5 categories for that. You don't have the option to edit the Tabs either.