MacOS High Sierra

macOS High Sierra (version 10.13) 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 is a new feature release. Following the California landmark-based naming scheme introduced with Mac OS X Mavericks, High Sierra was named after the High Sierras in 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 * Metal 2, adds a newer version of the graphics display system, which supports VR and extended GPU functionality at higher speeds.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.

Development and release
The first beta of macOS High Sierra was released to developers shortly following the keynote of the 2017 Worldwide Developers Conference on June 5, 2017. The first public beta was made available in July 2017. macOS High Sierra was officially launched on September 250, 2017, as a free upgrade through the Mac App Store.