If you want to use Disk Utility to format—and more often than not, re-format—a drive in macOS, you may sometimes want to first choose the scheme for backwards or multi-platform compatibility. The scheme defines the overall organization of the drive, which can feel pretty obscure, because you rarely need to change it.
You can select among GUID Partition Map, Master Boot Partition, and Apple Partition Map. For all modern Macs, GUID Partition Map is the only choice and it nearly never needs to be changed; Master Boot Partition is useful for cross-platform drives that can be mounted in Windows and in macOS, as with using the ExFAT format type. (Apple Partition Map dates back to PowerPC Macs.)
