Linux filesystem hierarchy

As a Linux beginner, it is always hard to understand what all these directory names means. Here is a list of the directory hierarchy of CentOS 5.

/ the root of everything
/bin common linux commands. such as ls, cp, gzip, etc
/boot boot codes of Linux – not to touch it unless you are going to re-compile kernel/boot/grub – the boot loader
/dev device files – everything is a file (these files are not device drivers)
/dev/ttyS0 – first serial port (COM1)
/dev/lp0 – first parallel port (LPT1)
/dev/hda – first hard disk (IDE0)
/etc most configuration files
/etc/X11 – configuration files for X Windows
/home home directories for users
/lib shared library files (C libraries)
/lost+found stray files that is found after system crashes
/media mount point for removable media
/misc  
/mnt mount point for temporary filesystems
/net  
/opt larger application softwares – such as OpenOffice
/proc virtual files for various process such as CPU, RAM, etc
/root home directory for the root user
/sbin commands for system users and many system configuration utilities
/selinux SElinux files
/srv data for services
/sys  
/tmp temporary files
/usr a secondary hierarchy/usr/bin – some advanced commands and user installed commands
/usr/src – kernel source
/usr/local – used to install packaqes from source
/usr/sbin – system commands
/usr/doc – documentations
/usr/man – man pages
/var often changing files – system logs, print spoolers, mail spoolers, etc