In the Linux file structure files are grouped according to purpose.  
Ex:
 commands, data files, documentation. All directories are grouped under the root entry "/".
  That part of the directory tree is left out of the below diagram.  See Filesystem standard.
- root - The home directory for the root user
 - home - Contains the user's home directories along with directories for services
 
- ftp
 - HTTP
 - samba
 - george
 
 - bin - Commands needed during bootup that might be needed by normal users
 - sbin - Like bin but commands are not intended for normal users. Commands run by LINUX.
 - proc - This filesystem is not on a disk.  It is a virtual filesystem that exists in the kernels imagination which is memory.
 
- 1 - A directory with info about process number 1. Each process has a directory below proc.
 
 - usr - Contains all commands, libraries, man pages, games and static files for normal operation.
 
- bin - Almost all user commands. some commands are in /bin or /usr/local/bin.
 - sbin - System admin commands not needed on the root filesystem. e.g., most server programs.
 - include - Header files for the C programming language. Should be below /user/lib for consistency.
 - lib - Unchanging data files for programs and subsystems
 - local - The place for locally installed software and other files.
 - man - Manual pages
 - info - Info documents
 - doc - Documentation
 - tmp
 - X11R6 - The X windows system files. There is a directory similar to usr below this directory.
 - X386 - Like X11R6 but for X11 release 5
 
 - boot - Files used by the bootstrap loader, LILO. Kernel images are often kept here.
 - lib - Shared libraries needed by the programs on the root filesystem
 
- modules - Loadable kernel modules, especially those needed to boot the system after disasters.
 
 - dev - Device files
 - etc - Configuration files specific to the machine.
 
- skel - When a home directory is created it is initialized with files from this directory
 - sysconfig - Files that configure the linux system for devices.
 
 - var - Contains files that change for mail, news, printers log files, man pages, temp files
 
- file
 - lib - Files that change while the system is running normally
 - local - Variable data for programs installed in /usr/local.
 - lock - Lock files. Used by a program to indicate it is using a particular device or file
 - log - Log files from programs such as login and syslog which logs all logins and logouts.
 - run - Files that contain information about the system that is valid until the system is next booted
 - spool - Directories for mail, printer spools, news and other spooled work.
 - tmp - Temporary files that are large or need to exist for longer than they should in /tmp.
 - catman - A cache for man pages that are formatted on demand
 
 - mnt - Mount points for temporary mounts by the system administrator.
 - tmp - Temporary files. Programs running after bootup should use /var/tmp.
 



