The fstab.conf file is a text file which contains the list of partitions and devices that Init uses to know where to find and mount the system devices and drives.
mine currently looks like this
/dev/hda2 / reiserfs defaults 1 1
/dev/hda6 /usr reiserfs defaults 1 2
/dev/hda7 /opt reiserfs defaults 1 2
/dev/hda8 /home reiserfs defaults 1 2
/dev/hda1 /windows ntfs ro 1 0
/dev/sr0 /mnt/cdrom iso9660 auto,user,owner,ro 0 0
/dev/hdd /mnt/dvd iso9660 auto,user,owner,ro 0 0
/dev/fd0 /mnt/floppy auto auto,user,owner 0 0
/dev/sda /mnt/usb vfat auto,user,owner 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
proc /proc proc defaults 0 0
You can add/edit any items and devices to the fstab. so for example my /dev/sda is my USB thumbdrive, so now when I want to mount it I can either type in the termian
or in gnome 2.6 I can just go to the "computer" desktop icon and double click on the "usb" drive and it will automatically mount it for me, reading the mount options straight from the fstab file.