File storage—also called file-level or file-based storage—is a hierarchical storage methodology used to organize and store data on a computer hard drive or on network-attached storage (NAS) device. In file storage, data is stored in files, the files are organized in folders, and the folders are organized under a hierarchy of directories and subdirectories. To locate a file, all you or your computer system need is the path—from directory to subdirectory to folder to file.

Source: IBM