If you're installing Windows 10 on a new hard drive or solid-state drive (SSD), it may already have unallocated space. However, if you're upgrading or replacing an existing installation, you might need to create unallocated space manually. Here’s how:
Dealing with unallocated space is a standard part of a clean Windows 10 installation . Unallocated space is essentially "raw" storage on your hard drive or SSD that hasn't been assigned to a partition yet, meaning the operating system cannot use it for file storage until it is formatted. How to Install Windows 10 on Unallocated Space unallocated space windows 10 install
