GNU/Linux Desktop Survival Guide
by Graham Williams
The default GNU/Linux file system (which defines how data is stored on a storage device like a hard disk) is call the ext2fs. Ext2fs is an inode (information node) based filesystem. Inode based file systems store pertinent file data in inodes. Such file systems have been around since the early days of Unix. Other inode-based file systems include XFS and BSD's UFS.
Ext3fs extends ext2fs with journaling. Thus, when you reboot without properly shutting down the machine, for example, no more messages about non clean un-mounts of the file system.
ReiserFS is a very different file system based on fast-balanced trees. It was proposed by Hans Reiser who took the theoretical concept of AVL-trees to the task of a filesystem.