Linux uses single rooted, inverted tree like file system hierarchy.
/ — This is top level directory
/root — It is home directory forroot user
/home — It is home directory for other users
/boot — It contains bootable files for Linux
/etc — It contains configuration like /etc/passwd
/usr — Default software’s are installed in this directory.
/opt — This is optional directory which contains third part softwares.
/bin — It contains commands used by all users.
/sbin — This contains commands used by only super user.
/dev — This contains device files.
/proc — It contains process files. Its contents are not permanent. They are keeps changing.
/var — This contains variable data like mails, log files,..
/mnt — It is default mount for any partition.
/media — It contains all of remove media like CD_ROM, External Hard Disk.
/lib — It contains library files which are used by Operating System. This is similar to dll files on windows.
/tmp — Location for temporary files.
/run — Contains process ID files and lock files.