With this method anyone can use one external drive for both your Windows PC and your Mac? One hurdle you'll face is that, by default, these platforms use different file systems. Windows uses NTFS and Mac OS uses HFS and they're incompatible with each other. However, you can format the drive to work with both Windows and Mac by using the exFAT filesystem.
In this guide we're using exFAT instead of FAT32, another filesystem that both Windows and Mac can read and write to, because FAT32 has a maximum 4GB file size limit whereas exFAT can work with files as large as 16EB (exabytes). exFAT also performs better than FAT32.
You can format the drive from either the Mac or the Windows machine. However, if you want to use part of the drive for OS X's Time Machine backups, you should do this from the Mac, since there's an extra step to make the drive compatible for Time Machine.
