Partitions to a drive can only be created when you are doing a full drive format. I will use my own reasons for this as examples. I am always making hardware changes to my computer, things like motherboards, RAM graphics cards, everything. Each time the Operating System has certain drivers installed for a specific piece of hardware. when that hardware changes it needs to be uninstalled and new drivers must be installed. In my experience, this only causes problems. I am an online gamer so I keep all my installed games onto a separate partitioned drive and everytime i change my hardware, i simply do a quick format on the OS partition, and reinstall the operating system completely. meanwhile all my games, communication software, etc are fully intact.
In other words...for back ups, partitioning space is ideal.
An individual would want to partition a hard drive for a variety of reasons. One of these reasons is to run multiple operating systems. Another reason is to create separate and manageable chunks of storage space.
In the likely event of a MS Operating System re-installation only the OS partition will need to be reformatted. All the data on the other partitions is safe.
importance of partitioning
The system partition(a partition where the operating system is installed) is the active partition of the Hard Drive
system partition
System partition
Most of the time the boot partition and the system partition are the same partition on the drive C.
The area on the hard drive that contains a map to all the partition on the drive is called the partition table. That is what partition utilities edit when you add, delete, convert, or resize a partition.
extended partition
Most of the time the boot partition and the system partition are the same partition on the drive C.
By default C: is the active partition of the hard disk drive
active partition
In general, there is no reason to have more than one partition on an external hard drive. There are some specific cases where it might be desirable but you would know if you had a requirement like that.
You just partition the Hard drive not the RAM.
Most of the time it is "C" the next drive letter in line would be "E" If you recently reformatted a single hard drive it will be "C" if you have another already formatted hard drive in your computer or you have a second partition it would be "E" So, unless you changed it, it is going to be "C".