MacOS Sierra

macOS Sierra, or macOS 10.12, is the thirteenth major release of macOS that was released on 20 September 2016. It was announced on 13 June 2016 at WWDC. It is the first version of Mac OS X to use the "macOS" branding for marketing materials, matching the rest of Apple's OS names (iOS, watchOS, tvOS, etc). It is the first version of macOS to drop support for Intel processors without SSE4.1.

New features and changes

 * The Siri virtual assistant from iOS has been added. It can be accessed via the Dock, the menu bar or through a keyboard shortcut.
 * iCloud Drive can now upload the user's documents and desktop directories and sync them to other devices.
 * Optimized Storage was added to System Information. It provides suggestions for freeing up disk space and gives the user detailed information about space usage per application.
 * Auto Unlock has been added. It allows the user to unlock their Mac by holding a paired Apple Watch close to the Mac. It requires a Mac released in 2013 and later.
 * Universal Clipboard has been added. It allows the user to share the clipboard for cut, copy and paste between macOS and iOS devices, including text and rich content, such as pictures or videos.
 * Applications that support multiple windows can now have multiple tabs similar to Safari.
 * Picture-in-Picture support was added. It allows videos to be played in a floating window.
 * macOS Sierra 10.12.4 adds Night Shift which reduces blue light at night to help with sleep.
 * The Photos app adds improved face recognition and adds Memories which groups similar pictures using faces, locations and object recognition.
 * Safari changes how legacy plug-ins behave. It also adds support for paying things online with Apple Pay.
 * The Messages app received support for aesthetic effects and the ability to play YouTube videos and preview links in a conversation.
 * Apple Music has been redesigned to make it easier for the user to discover and find songs.
 * The Notes app allows the user to share and collaborate on notes.
 * The Gatekeeper received a minor UI redesign and adds two new mechanisms.
 * The Game Center app has been removed like in iOS 10. However, the service itself still exists.
 * A control button on top of email lists in the Mail app which allows the user to quickly filter them.
 * Finder can now show folders always at the top of the view hierarchy.