The Filesystem Hierarchy Standard (FHS) defines the directory structure and directory contents in Linux distributions.
Directory structure on Debian
In addition to the directory structure described in the FHS, the following directories can be found on Debian systems:
- /lost+found/ : File fragments that were recovered during the previous fsck
http://www.debian.org/releases/etch/amd64/apcs02.html - Debian Directory tree overview
https://wiki.linuxfoundation.org/lsb/fhs - The FHS Linux Foundation wiki page
http://refspecs.linuxfoundation.org/fhs.shtml - FHS 3 Specification Series
http://www.debian.org/doc/packaging-manuals/fhs/ - Debian mirror of the FHS