Rolling out to all Gmail users now.
Gmail continues to be one of the most popular email clients on Android, and today Google's adding support for various "Inbox Types." This is something that's been available on desktop for some time, and it enables you to customize the various priorities of the emails you receive.
First and foremost, if you have a specific inbox type that you use while accessing Gmail on your computer, you'll now see that same setup in the Android app. For example, if you want your unread messages at the top of your inbox and everything else to populate below them, you'll now see those changes reflected in the Android app.
In addition to this, you can hop into Gmail's settings on your phone to change the inbox type you're currently using.
To do this, go to Settings -> Inbox type, and then choose the one you want – including Default Inbox, Important first, Unread first, Starred first, and Priority Inbox.
This is rolling out to all Gmail users starting today, and it should be widely available over the coming days.