Simple definition
The chroot command changes a process's apparent root directory; it is not a complete security isolation boundary.
Purpose and use
chroot is useful when working inside the directory tree of a system being repaired or a separately prepared environment.
How does it work?
Absolute paths are resolved from a new root directory, and child processes inherit that view.
Example and verification
Check that required programs and libraries are available inside the selected tree.
Points to watch
chroot alone does not isolate processes, networking or privileges; it is not a complete security boundary.
In short
Changing the visible root is different from creating a container or virtual machine.