FHS – Filesystem Hierarchy Standard

Directory Purpose
/ Root directory of the entire file system hierarchy
/bin Essential command binaries (all users)
/boot Boot loader files.
/dev Device Files
/etc Host specific system wide configuration files
/home Users home directories
/lib Libraries essential for /bin and /sbin
/media Mount points for removable media
/mnt Temporary mounted file systems
/opt Optional application software packages
/proc Virtual filesystem containing information about processes
/root Home directory for the root user
/sbin Essential system binaries (root only)
/srv Data for services provided by this system
/tmp Temporary files
/usr Secondary hierarchy for read only user data
/usr/bin Non Essential command binaries
/usr/include Standard include files
/usr/lib Libraries for the binaries in /usr/bin and /usr/sbin
/usr/local Local data. Normally contains sub-directories bin/, share/
/usr/sbin Non Essential system binaries
/usr/share Architecture shared independent data
/usr/src Source code
/var Variable files such as logs
/var/cache Application cache files
/var/lock Lock files
/var/log Various log files
/var/mail Users mail boxes
/var/run Information about running system since last boot
/var/spool Spool for task waiting to be processes – print queues – unread mail
/var/tmp Temporary files preserved between boots