So I have an external harddrive that i used on my PC and now i want it to work with my mac? i know it has to do with the format NT and FAT but i'm not sure how to do it. So any help would be a big help.
if you want it to be able to be read by both your PC and Mac, you'll have to format it as FAT32. if you're going to just use it with your Mac, format it as HFS (Mac OS Extended)
and yes, formatting it will erase all data on the drive, so if it has anything important back up the data first.