Most computer users nowadays rely on online file storage. Thanks to the rise of cloud computing, the idea of storing files remotely and downloading them when needed has gained a lot of fresh air in recent years. Yet, the principle's technical roots are anything but new, with implementations reaching back decades. While the protocols used and features expected for accessing data on online storage have changed massively, the basic idea hasn't altered much since the days of FTP and similar protocols.
There's an easy explanation for why online (or "cloud") storage has so many fans. Cloud storage usually resides on highly redundant infrastructure, often distributed across physical sites. Ordinary people would have a tough time setting up anything similar with the tools generally available to them. Cloud storage also allows users to extend their storage space easily without having to fiddle with their device hardware. It also enables people to share files with relatives, friends, or colleagues in just a few simple steps.
Smartphones are an excellent example of cloud storage's advantages; clients including Dropbox, Google Drive, and iCloud are deeply integrated into mobile operating systems and can be used in apps just like local storage.