A small-board computer (SBC) is a compact system that can run the same software as a desktop PC on some Linux flavor or Windows. They're capable devices with powerful processors, upgradable and expandable parts, and healthy modding ecosystems. You can find SBCs powering surveillance systems, media centers, and storage solutions. It's possible to transform an SBC into a network-attached storage (NAS) server where you can store backups, sensitive data, and more. Compared to pre-built NAS enclosures from Synology, Asustor, and other brands, this could save you money.
Source: xda-developers.com