1# File Systems 2 3A file system \(often abbreviated to FS\) provides an input and output manner for an OS. It implements the interaction with internal and external storage devices. 4 5The file system provides standard POSIX operation APIs for the upper-layer system through the C library. For details, see the API reference of the C library. The Virtual File System \(VFS\) layer in kernel mode shields the differences between file systems. The basic architecture is as follows: 6 7**Figure 1** Overall file system architecture 8 9 10- **[Virtual File System](kernel-small-bundles-fs-virtual.md)** 11 12- **[Supported File Systems](kernel-small-bundles-fs-support.md)** 13 14- **[File System Adaptation](kernel-small-bundles-fs-new.md)** 15 16 17
