That's nearly a week after the iOS 11 and watchOS 4 release date, with those software updates coming on Tuesday, September 19. It is not unusual for the Mac operating system to be released after new watchOS and iOS operating system updates.
macOS High Sierra builds on features first introduced in the macOS Sierra update in 2016, focusing primarily on new storage, video, and graphics technology. The update brings a new Apple File System (APFS), High Efficiency Video Codec (HEVC), new HEIF image encoding, and an updated version of Metal with support for VR and external GPUs.
Multiple apps have been updated with new capabilities in macOS High Sierra. Photos features a new sidebar to make it easier to access editing tools and albums, and there are new filters and editing options like Curves and Selective Color.
Safari is gaining speed enhancements, an option to prevent autoplay videos, and a privacy feature aimed at cutting down on cross-site data tracking. Siri in macOS High Sierra has a new, more natural voice, and Spotlight offers flight status information. iCloud, FaceTime, Notes, and Mail also include useful new features.
macOS High Sierra will run on all machines that are capable of running macOS Sierra, the current Mac operating system.
For a complete overview of changes coming in macOS High Sierra, make sure to check out our macOS High Sierra roundup.