I just purchased an external HDD on which I planned to back up my internal HDD. When I cut and paste all the files from C: into the external, it only shows that it is copying approximately 87gbs. However, when I click properties on my C: and look at the amount of space that is already being utilized it is around 170gbs. What is taking up all that space and why isn't it being copied onto my external? Thanks.
It is probably not copying all the files, likely system files and such that you don't have permission to copy. You don't need to copy the entire disk like that to get a backup, most of the time you can just copy your user folder in C:\Users. You might want to use the built in windows backup tool.