Last month, Google released an update to the Gmail inbox to help users easily identify the messages that matter to them and ignore the rest. The new inbox feature works by auto-sorting email as it arrives in your inbox into predefined tabs including Primary (typically non-commercial email from coworkers and friends), Social, Promotions, Updates and Forums.
The filters also work with the Gmail Mobile app for Android and iOS. The mobile inbox doesn't use tabbed categories; instead, small tags act as shortcuts to the Social and Promotions category folders.
To use the new features, simply open Gmail, click on the gear icon on in the upper-right corner and select the Configure inbox. Then check the boxes of the tabs you want to see, and save. Don't like the new look? You can switch back easily by hovering over your inbox and following the menu prompts that pop up.