Michael Potuck, 9to5Mac:

Files replaces the iCloud Drive app in iOS 11 and brings a number of enhancements to working with your files on your iPhone and iPad. There is a Browse and Recents tab at the bottom of the Files app. In the Browse tab you can easily navigate between files stored on iCloud or on your device, a Recently Deleted location along with Favorites, and Tags. Let’s dive into some of the details.

Even if you are not running the iOS 11 beta, this is easy to follow and an important concept that comes with iOS 11.