MacOS Sierra is finally out of beta -- which means you can download the final version for free from the Apple Store. Get it here.
While it's not a "major" upgrade, the latest version of MacOS X ushers in some extremely useful features including Siri integration for the first time. This means you can now use Apple's digital assistant to ask for directions, check appointments and access documents with your voice.
Other noteworthy improvements include a universal clipboard that works with iOS 10, automated iCloud syncing for your Documents and Desktop folders and an in-built storage optimisation tool. (For a more detailed breakdown of new features, click here.)
The upgrade clocks in at around 4.4GB and is compatible with OS X 10.7 or later. Naturally, it's a good idea to make a Time Machine backup prior to installation. Here's the link to the free download.