/tmp - This directory contains mostly files that are required temporarily.

Many programs use this to create lock files and for temporary storage of

data. On some systems, this directory is cleared out at boot or at

shutdown.

/usr - This is one of the most important directories in the system as it

contains all the user binaries. X and its supporting libraries can be

found here. User programs like telnet, ftp etc are also placed here.

/usr/doc contains useful system documentation. /usr/src/linux contains the

source code for the Linux kernel.

/var - This directory contains spooling data like mail and also the output

from the printer daemon. The system logs are also kept here in

/var/log/messages. You will also find the database for BIND in /var/named

and for NIS in /var/yp.

This was a short and basic look at the Linux filesystem. You do need to

have at least this basic knowledge of the layout of the filesystem to

fully utilize its potential. One good place to read about the filesystem

is this detailed document at www.pathname.com/fhs/1.2/fsstnd-toc.html that

specifies the standard structure of the Linux filesystem.