What is MacOS Sierra? Description of MacOS Sierra 3564 chars

Siri makes its debut on Mac, with new features designed just for the desktop. Your Mac works with iCloud and your Apple devices in smart new ways, and intelligent capabilities make your photos, music, and messaging even more enjoyable.  

Get things done by asking Siri, the intelligent assistant now on your Mac.
• Enjoy your favorite features from iOS as well as new ones optimized for Mac.
• Send messages, create reminders, search the web, and more while you work.
• Drag and drop or copy and paste Siri results into your documents.
• Pin Siri results in Notification Center and reference them later.
• Find files, adjust settings, and get system information just by asking Siri.  

Copy and paste between your devices with Universal Clipboard.
• Copy a quote, image, or video from an app on one device and paste it into an app on another device.

Automatically log in with Auto Unlock.
• Log in to your Mac automatically when you wear your Apple Watch — no need to type your password.

Enjoy the convenience and security of Apple Pay when you shop on the web.
• Use Apple Pay to make easy, secure payments when shopping in Safari on your Mac.
• Complete your purchase with Touch ID on your iPhone or with your Apple Watch.

Access files on your Mac desktop from your iPhone with iCloud Desktop and Documents.
• Automatically store all the files on your desktop and in your Documents folder in iCloud, and access them from all your devices.
• Keep the same desktop and Documents folder on your other Mac.  Easily free up space on your Mac with Optimized Storage.
• Automatically store seldom-used files in iCloud, where they’ll be available on demand.
• Additional tools help you remove files you don’t need, to save even more space.

Get control of your desktop with tabs in apps.
• Use tabs to manage multiple windows in Maps, Pages, Keynote, Numbers, and more.
• Work with tabs in your favorite third-party apps — no developer adoption required.

Keep an eye on the big game or your favorite video with Picture in Picture.
• Float a video window from Safari or iTunes over your desktop as you work.
• Place the Picture in Picture window in any corner, and it stays put when you switch spaces or work in full screen.

Rediscover the most meaningful moments in your Photos library.
• Enjoy favorite and forgotten occasions from your photo library with Memories.
• View your images by who’s in them. Photos uses advanced face recognition technology to automatically group photos of the same person together.
• Search your photos by what’s in them, such as beaches, dogs, or concerts, thanks to intelligent search that can recognize objects and scenes.
• Track your photo expeditions across an interactive world map. 

Enjoy an all-new Apple Music experience in iTunes.
• Easily navigate your library with the redesigned Apple Music.
• Discover great new music thanks to expert curation and advanced machine learning that give you the best recommendations.

Liven up your Messages conversations.
• See web content previews and watch web videos right in a conversation.
• Respond to messages with quick, handy Tapbacks.
• Express yourself with 3x larger emoji.
• View the stickers, Digital Touch, invisible ink, and handwritten messages that friends send from their iOS devices.  

Some features may not be available in all regions or all languages. Some features have hardware requirements. Some features require an iCloud storage plan.