Command (m for help): p

Disk /dev/hda: 240 heads, 63 sectors, 2184 cylinders
Units = cylinders of 15120 * 512 bytes

Device Boot    Start       End    Blocks   Id  System
/dev/hda1             1        14    105808+  83  Linux
/dev/hda2            15        49    264600   82  Linux swap
/dev/hda3            50        70    158760   83  Linux
/dev/hda4            71      2184  15981840    5  Extended
/dev/hda5            71       209   1050808+  83  Linux
/dev/hda6           210       348   1050808+  83  Linux
/dev/hda7           349       626   2101648+  83  Linux
/dev/hda8           627       904   2101648+  83  Linux
/dev/hda9           905      2184   9676768+  83  Linux

Command (m for help): 

In our example, hda1 through hda3 are primary partitions. hda4 is an extended partition that contains logical partitions hda5 through hda9. So, in this example, you would never actually use /dev/hda4 for storing any filesystems directly -- it simply acts as a container for partitions hda5 through hda9. Also, notice that each partition has an "Id", also called a "partition type". Whenever you create a new partition, you should ensure that the partition type is set correctly. '83' is the correct partition type for partitions that will be housing Linux filesystems, and '82' is the correct partition type for Linux swap partitions. You set the partition type using the t option in fdisk. The Linux kernel uses the partition type setting to auto-detect filesystems and swap devices on the disk at boot-time.