File System Hierarchy (FHS)

Directory	Description
/	Primary hierarchy root and root directory of the entire file system hierarchy.
/bin/	Essential command binaries that need to be available in single user mode; for all users, e.g., cat, ls, cp.
/boot/	Boot loader files, e.g., kernels, initrd; often a separate partition[8]
/dev/	Essential devices, e.g., /dev/null.
/etc/	Host-specific system-wide configuration files (the name comes from et cetera[9]).
/etc/opt/	Configuration files for /opt/.
/etc/X11/	Configuration files for the X Window System, version 11.
/etc/sgml/	Configuration files for SGML.
/etc/xml/	Configuration files for XML.
/home/	Users' home directories, containing saved files, personal settings, etc.; often a separate partition.
/lib/	Libraries essential for the binaries in /bin/ and /sbin/.
/media/	Mount points for removable media such as CD-ROMs (appeared in FHS-2.3).
/mnt/	Temporarily mounted filesystems.
/opt/	Optional application software packages[10].
/proc/	Virtual filesystem documenting kernel and process status as text files, e.g., uptime, network. In Linux, corresponds to a Procfs mount.
/root/	Home directory for the root user.
/sbin/	Essential system binaries, e.g., init, route, mount.
/srv/	Site-specific data which is served by the system.
/tmp/	Temporary files (see also /var/tmp). Often not preserved between system reboots.
/usr/	Secondary hierarchy for read-only user data; contains the majority of (multi-)user utilities and applications.[11]
/usr/bin/	Non-essential command binaries (not needed in single user mode); for all users.
/usr/include/	Standard include files.
/usr/lib/	Libraries for the binaries in /usr/bin/ and /usr/sbin/.
/usr/sbin/	Non-essential system binaries, e.g., daemons for various network-services.
/usr/share/	Architecture-independent (shared) data.
/usr/src/	Source code, e.g., the kernel source code with its header files.
/usr/X11R6/	X Window System, Version 11, Release 6.
/usr/local/	Tertiary hierarchy for local data, specific to this host. Typically has further subdirectories, e.g., bin/, lib/, share/.[12]
/var/	Variable files—files whose content is expected to continually change during normal operation of the system—such as logs, spool files, and temporary e-mail files. Sometimes a separate partition.
/var/lib/	State information. Persistent data modified by programs as they run, e.g., databases, packaging system metadata, etc.
/var/lock/	Lock files. Files keeping track of resources currently in use.
/var/log/	Log files. Various logs.
/var/mail/	Users' mailboxes.
/var/run/	Information about the running system since last boot, e.g., currently logged-in users and running daemons.
/var/spool/	Spool for tasks waiting to be processed, e.g., print queues and unread mail.
/var/spool/mail/	Deprecated location for users' mailboxes.
/var/tmp/	Temporary files to be preserved between reboots.