MacOS High Sierra is the new operating system of Apple that has already arrived in beta form to be available in autumn to anyone who wants to install it.
It brings many improvements and is compatible with virtually any Mac computer that can install macOS Sierra.
One of the most important changes? The arrival of APFS, but that yes, Apple leaves to your choice to use the new file system or not to use it.
As we can see in Faq-Mac, at the moment in the first beta of macOS High Sierra we are not required to use the APFS file system.
When performing the update to macOS High Sierra we are asked if we want to also update the hard disk or SSD to APFS.
This is probably due to the fact that it is not recommended to use APFS on HD disks since it is a file system optimized for SSD with encryption, high speeds, and many other changes. That is if you offer the option is for computers with hard drive also can use macOS High Sierra.
As we have seen on other occasions, APFS is the future of Apple computers
It is a more stable system, optimized for devices with SSD memory, supports 64 bits, does not duplicate files but creates metadata to redirect to the original file, manages improvements to the partitions, reduces the latency of access to data and above all, considerably improves the Security through its encryption system.