In order to use a hard drive, or a portion of a hard drive, in Windows you need to first partition it and then format it. This process will then assign a drive letter to the partition allowing you ...

Step by step tutorial on how to format a Hard Drive or Disk. Use built-in tools such as Diskpart, CMD, Disk Management, etc, to format.

A drive formatted in this fashion can be swapped between a Mac and Windows PC. However, you might choose instead a format you can use easily with OS X, Windows, and Linux.