There are three types of disk partitions: primary partition, extended partition and logical partition. A hard disk has 1-4 primary partitions. And it has 1 extended partition at most. And the total number of primary partitions and extended partition must be less than 4. And it may have several logical partitions.
The activated primary partition is boot partition of disk and it is independent. It is also the first partition, Drive C: usually.
When the primary partition is divided, all of the left part can be divided into extended partitions usually. Otherwise, the space not divided will be wasted. But the extended partition can not be applied directly. It is used in the form of logical partitions. So the extended partition can be divided into several logical partitions. Their relations are inclusion relation and all logical partitions are a part of the extended partition.
In Linux, capacity of hda partition disk = capacity of primary partitions + capacity of extend partition and capacity of extended partition= capacity of all logical partitions. The primary partition is also called "boot partition", and the operating system and main board will consider it as the first partition of the disk. Therefor, Disk C is always in the first place of all disk partitions. Apart from the space taken up by primary partition, the space left is considered as extended partition. In other words, the primary partition is the master of disk, and the extended partition is slave of disk. The relationship of the primary partition and the extended partition is master- slave relation. If the extended partition is not divided, it will be considered ad logical partition. And if partition operation is needed, logical partitions must be divided from the extended partition. It means that the extended partition is subclassified to Disk D:, Disk E: and Disk F: for different uses.
In the process of using computer, as the increase of data stored in disk, it may be necessary to adjust the capacity of primary partition or extended partition. And the "Disk Management" in operating system can not make it. So the third-party disk management tool is needed. MiniTool Partition Wizard is a free partition magic for disk partition management, and it supports almost all Windows operating system and Ext2, Ext3 and Swap partitions in Linux. It is so easy and convenient to adjust the sizes of primary partition and extended partition. And the adjustment will not cause data loss or damaged. The detailed informations are in Resize Partition Help Center