Major Difference between DAS,NAS and SAN??

What are all the Directories present in UNIX ??

/bin -Essential command binaries
/boot -Static files of the boot loader
/dev -Device files
/etc -Host-specific system configuration
/lib -Essential shared libraries and kernel modules
/media -Mount point for removeable media
/mnt -Mount point for mounting a filesystem temporarily
/opt -Add-on application software packages
/sbin -Essential system binaries
/srv -Data for services provided by this system
/tmp -Temporary files
/usr -Secondary hierarchy
/var -Variable data