

Solution #1: Create a new partition on unallocated space In such circumstances, it is not recommended to try creating new partition or expanding partition at once, the correct move is recovering lost files or searching for lost partitions first. It is worth noting that sometimes unallocated space is the result of faulty operations, for instance, you delete a partition by mistake, partition table gets corrupted and all partitions are disappeared, etc. After extending partition, this portion of space will be the free space which can be access by system. In addition to creating a new partition, you can also use unallocated space by merging it to an existing partition.
Move unallocated space to an existing drive. After creating partition and formatting, Windows will be able to recognize and make use of it.

Since unallocated space is not part of any partition, you can simply create a new partition on it. How to use and allocate unallocated space on hard drive, SSD, SD card or USB flash drive? On balance, there are two approaches to cope with the issue:

If you delete or shrink an existing partition, you will get unallocated space. Operating system cannot access it, and yet you can view it in Disk Management. Physical disk space that does not belong to a partition is called unallocated, and thus it is unable space. Hence, you need to create one or multiple partitions on a physical hard drive/SSD, for example, C drive, D drive, etc. Without partition, unallocated space cannot be used to store files or install system. What does unallocated space mean? When you install Windows, the installer will prompt to partition hard drive and format partition first. Does that mean the unallocated space cannot be merged to C drive?" However, when I right-clicked C drive, the option "Extend Volume" is inactive. In Disk Management, I shrunk D drive and got 100GB unallocated space which is between the Recovery and D drive. C drive is running out of space, so I want to move some free space from D to C. "Can someone here tell me how to allocate unallocated space to c drive in windows 10? The internal hard drive is 5GB and it is partitioned into 4 partitions, they are EFI system partition, C drive, Recovery and D drive in sequence. What is unallocated space and how to make use of it?
