It's simply called the Apple File System (APFS), and it's the first format to be used across both Macs and iOS devices. With the release of the macOS High Sierra operating system, Cupertino ditched its venerable Mac OS Extended file system, commonly abbreviated as HFS+, and switched to an entirely new file system. Before we get to Thunderbolt 3, we need to address a basic building block of hard drives that has always affected compatibility, and probably always will: the file system.Īn external drive's file system is the most important factor that determines whether or not it's readable by Macs, PCs, or both.
