File System
Problem
A process exits and its RAM disappears.
But documents, configuration and application data must survive.
We also need a way to organize millions of stored pieces of data.
Solution — File System
A file system organizes persistent data into files and directories.
/ ├─ home ├─ etc └─ var
It manages names, metadata, permissions and mappings to storage.
When you attach another disk, applications need a path to reach its files. Mounting makes its file system accessible at a location called a mount point—for example, mounting it at /data makes its files available under /data.
During boot, Linux mounts a root file system at /, providing the starting directory tree. Other file systems, backed by disk partitions, USB drives, or network storage, can be mounted into that tree and unmounted when no longer in use.
Core idea: file systems organize persistent data and give applications a standard way to access it.