virtual filesystem
also: VFS, Virtual File System
An abstraction layer that provides a unified interface to different filesystem types, allowing the kernel to treat all filesystems (local disks, network drives, RAM-based systems) uniformly regardless of their underlying implementation.
The Virtual Filesystem (VFS) is a kernel subsystem that sits between user applications and actual filesystem implementations. It defines a common set of operations—like open, read, write, and close—that every filesystem must support, enabling the kernel to manage multiple filesystem types transparently.
Instead of applications needing to know whether they're accessing ext4, NFS, or tmpfs, they interact with the VFS layer, which translates their requests into the appropriate filesystem-specific calls. This allows you to mount different filesystem types at different mount points and access them all through the same path interface.
For example, you might have / on ext4, /mnt/network on NFS, and /dev/shm on tmpfs, but applications access all three using standard file operations without caring about the underlying type.