When you think about your smartphone, apps and interfaces are probably the first things that come to mind. Beneath all that surface-level stuff, though, our modern mobile devices are filled with files — folders upon folders of 'em! — just like the clunky ol' computers we've relied upon for ages.
We may not come face to face with our phones' file systems too often, but it's valuable to know they're there — and to know how they can work for us when the need arises. After all, your Android device is a productivity powerhouse. It can juggle everything from PDFs and PSDs to presentations and podcasts. It can even act as a portable hard drive and house any sort of important files you might need in your pocket (and not just on some far-away cloud). Your mobile device can carry an awful lot of data, and there may come a time when you want to dig in and deal directly with it.