Formatting an external hard drive.
External Hard drives do not always arrive ready to use with your individual computer system, it may need to be re-formatted prior to use.
If you are working with a mac computer at home, and don't ever use Windows systems, I would advise formatting into Mac OS Extended Journaled, or one of the equivalent encrypted if you like to use passwords for your hard drives.
If you work with both Mac and Windows, you can either use ExFAT or partition your hard drive into two sections, one formatted for Mac OS and the other in NTFS.
If you use a windows computer and don't ever need compatibility with mac systems, NTFS is the standard windows format.
Some external hard drives or flash drives come formatted in FAT32. This is an older system which, similar to ExFAT, is technically compatible with both Mac and Windows, however it has an individual file size limit of 4GB, which while fine for general use, becomes hugely problematic during video editing where file sizes can be much larger. I would therefor always advise re-formatting to one of the above suggestions if you find your drive is FAT32.