It is not uncommon to need to partition a hard drive during installation into several parts. This structure of the system not only allows you to "divide" the HDD into sectors, but is also useful when reinstalling the OS.
This is especially useful when you have to reinstall Windows due to viruses, since the OS installation formats only the system drive, that is, "Local Disk `C`". During the Windows installation process, there will be a step where you will be given the opportunity to build the system structure.
As an example, let's partition a 476 GB HDD into three sectors.
1) Press the "C" button, after which, a window of this type will appear. 
2) First of all, be sure to create the system disk "C", allocate 100 GB of memory to it (the size is set in megabytes). After that, press "Enter". 
3) Press the "C" button again, after which, you go to the page for creating a new partition. 
4) Again specify 100 GB for the new partition and press "Enter". 
5) Press the "C" button again.
6) Specify all the remaining space on the HDD.
That is, you do not specify anything this time, since the installer will automatically specify the maximum available memory. Press "Enter".
7) Select the "C" partition for formatting and installing the OS.
That's all: now you will have 3 partitions on the HDD.
- First partition "C" with a size of 100 GB for the Windows OS.
- Second partition with a size of 100 GB for your needs.
- Third partition with a size equal to the remaining memory on the HDD, also for your needs.
Read more articles about the hard drive:
- Two partitions on a hard drive
- Windows stopped seeing the hard drive
- Hard drive is slowing down - what to do?
Good luck!
