MacOS High Sierra

macOS High Sierra (version 10.13), first released on September 25, 2017, is the fourteenth major release of OS X, renamed macOS, Apple's desktop and server operating system for Macintosh computers. It is the successor to macOS Sierra and the predecceesor of macOS Mojave. Following the California landmark-based naming scheme introduced with Mac OS X Mavericks, High Sierra was named after the High Sierra region of the Sierra Nevada mountain range.

New features
The following is a partial list:
 * New APFS file system, also introduced in iOS 10, replaces the decades-old HFS+ drive format with a modern replacement.
 * HEVC, adds support for a much more efficient H.265 video codec.
 * Metal 2, adds a newer version of the graphics display system, which supports VR and extended GPU functionality at higher speeds.
 * Integrated VR support, contains support for creating, editing and interacting with VR media.
 * Photos, adds an expanded sidebar, improved organization tools, integrates with advanced editing tools, supports more Memories modules and live photo editing tools, and included People/Faces.
 * Safari, now contains Intelligent Tracking Prevention, the ability to disable autoplay, site-based browser settings, site-based always-on reader view.
 * Siri, supports preference learning for music and is more tightly integrated with iTunes, and text to speech is improved.
 * Spotlight, adds flight tracking features.
 * Mail Search, is improved with more options.
 * FaceTime, supports capture of Live Photos from streaming video.
 * Notes, adds pins and tables.

System requirements
macOS High Sierra runs on the following Macintosh models with at least 2 GB of RAM and 14.3 GB of available disk space:
 * iMac: Late 2009 or later
 * MacBook: Late 2009 or later
 * MacBook Pro: Mid 2010 or later
 * MacBook Air: Late 2010 or later
 * Mac Mini: Mid 2010 or later
 * Mac Pro: Mid 2010 or later

HEVC hardware acceleration requires a Mac with a sixth-generation Intel processor or newer:
 * iMac: Late 2015 27" or later, Mid 2017 21.5" or newer
 * MacBook: Early 2015 or later
 * MacBook Pro: Mid 2016 or later
 * iMac Pro

External graphics processor support requires a Thunderbolt 3-enabled Mac:
 * MacBook Pro: Late 2016 or later
 * iMac: Mid 2017 or later
 * iMac Pro

It is possible to install High Sierra on many older Macintosh computers that are not officially supported by Apple. This requires using a patch to modify the install image.

Deprecation of 32-bit support
Apple notified developers that High Sierra would be the last version of macOS to run 32-bit applications "without compromise". Starting with the update to macOS 10.13.3, launching a 32-bit application would display an alert that it "is not optimized for your Mac. This app needs to be updated by its developer to improve compatibility." macOS Mojave (10.14) would be the final major release to even run 32-bit software at all. MacOS Catalina (10.15) would mark the completion of Apple's transition to 64-bit technology and no longer support 32-bit applications.

Development and release
The first beta of macOS High Sierra was released to developers shortly after the keynote of the 2017 Worldwide Developers Conference on June 5. The new features were presented by Craig Federighi, the senior VP of software engineering. When discussing how the "crack marketing team" came up with the name High Sierra while traveling in their minibus, he joked that they "assured us this name is fully baked."

The first public beta was made available in July 2017. macOS High Sierra was officially launched on September 25, 2017, as a free downloadable upgrade through the Mac App Store. There is no physical retail version from Apple, though it is possible to create a bootable drive of the installer.