moving files to external hard drive

Use external storage devices with Mac - Apple Support

how can I determine if the transfer of my files to an external hard drive was successful?

Choose the External drive under Devices in your Finder Sidebar. That will show you all the folders and files on the drive.

Thanks!

You're welcome.

I was able to reformat my external hard drive but it's not showing up in my "finder" or anywhere. only under the utilities file but I can't do anything to it. It's not opening when I connect it either...I can't figure this out! How do I save files to it. Please help! This is driving me crazy!!!!

Not listed under "Devices" in Finder Sidebar?

FYI, "Devices" is now known as "Locations" - in macOS Catalina.

Thanks for mentioning that. The OP hasn't posted any specs, so it could be any OS.

You are most welcome, 'macjack'. 😀