Answer» What is Filesystem Hierarchy Standard mean?
The Filesystem Hierarchy Standard (FHS) defines the directory structure and directory contents in Linux distributions. It is maintained by the Linux Foundation. The latest version is 3.0, released on 3 June 2015.
Linux distributions (and other operating systems) can voluntarily conform to the FHS. The Freedesktop.org project provides a specification called XDG Base Directory Specification that is intended to extend FHS by various environment variables and paths where some user-specific applications files should be stored.