- macOS Sierra - The latest Apple's operating system for Macintosh computers. Previously named OS X, macOS 10.12 "Sierra" was announced at WWDC 2016. During the keynote, Apple announced that OS X would be renamed macOS to stylistically match Apple's other operating systems, such as iOS, watchOS, and tvOS. New features announced during the keynote include the addition of Siri, Optimized Storage, and updates to Photos, Messages, and iTunes.
Siri makes its debut on Mac, with new capabilities designed just for the desktop. And that’s not the only way your Mac is smarter. macOS Sierra helps you rediscover your best photos, shop more securely online, and work more seamlessly between devices. It can also help free up valuable storage space. Now your Mac does even more for you, so you can do more with your Mac.
MacOS Sierra 10.12 Developer Preview.dmg