If the "Extend Volume" option in Windows Disk Management is grayed out, you might want to try AOMEI Partition Assistant. It is easy to fix the problem, and no data will be lost.

Learn how to use Disk Management Tool in Windows 11/10 to create a new partition, extend a partition, shrink a partition, format and more.

Unallocated Disk Space can be assigned its own volume letter or used to extend another drive. Types of Partitions are also explained.

You can group two or more hard drives on your Windows 10 PC to create a single large volume to store your data. Here's is how to do it.