macOS Sierra (version 10.12), released September 20, 2016, is the thirteenth major release of OS X, renamed macOS, Apple's desktop and server operating system for Macintosh computers. It is the successor to OS X El Capitan and is a new feature release. Following the California landmark-based naming scheme introduced with OS X Mavericks, Sierra was named after the entire Sierra Nevada mountain range that includes Yosemite National Park and Lake Tahoe.
The following is a shortened new feature list:
- Siri integration, including drag-and-drop
- Auto Unlock via paired devices such as an Apple Watch
- Universal Clipboard shared between devices using the same Apple ID
- Desktop and Documents Sync, syncing the desktop and documents folders via the cloud so the same desktop is available everywhere
- Photos now contains local intelligent systems processing to find relationships between photos and makes them available via search or browsing
- Apple Pay Integration, where linked devices with Apple Pay can be used to pay via Safari.
- Picture-in-Picture support for Safari and iTunes, which allows users to watch videos while working in other applications
- Messages gets a major refresh and now allows users to integrate rich media into one's texts
- Apple Music is fully rebranded and has a new interface
- Optimized Storage, where old items can be moved off-disk onto iCloud storage
- Safari-style Tabs, where tabs are now a UI feature inherited by Cocoa applications, not just Safari, Terminal and the Finder.
The first beta of macOS Sierra was released to developers shortly following the 2016 WWDC keynote on June 13, 2016. The first public beta was made available in July 2016. macOS Sierra was officially launched on September 20, 2016, as a free upgrade through the Mac App Store.
The Developer Beta also includes a new Apple File System (APFS) to replace HFS+, but the release version of APFS isn't due out until macOS 10.14 in 2017.