Microsoft’s final release version of Windows 8.1 arrived Thursday with downloads available for owners of Windows 8 computers and devices in 230 markets and 37 languages, the company said.

On Friday, the software giant will make available the first products pre-loaded with Windows 8.1, and will also begin selling boxed software editions of the OS update through retail partners.

“With Windows 8, we introduced an era of highly mobile, touch-enabled, and always-connected computing. Windows 8.1 evolves this vision and brings together everything people do across all their devices whether at home, at work, or on the go,” Microsoft said in a statement. “Windows is delivering the most personal computing experience out there, making your device a unique extension of you and offering more ways to create an experience that is personal, expressive and keeps pace with your life.”

Introduced as a preview version at Microsoft’s Build developer conference in June, Windows 8.1 is the first major update to Windows 8, which was released on Oct. 26, 2012.

Perhaps the most talked-about feature of Windows 8.1 is the return of the familiar and popular Windows Start button, which Microsoft temporarily abandoned with the first live-tile interface featured in Windows 8.

Microsoft is also banking on several more new features and improvements in the update to its flagship operating system to give a boost to the less-than-stellar adoption rates of Windows 8.

Windows 8.1 offers a more customizable Start screen in live-tile mode as well as the option for the old Windows desktop version, syncs all Windows devices with a user’s Microsoft account, offers a one-stop App menu and a new Help + Tips app, introduces enhanced Bing Smart Search for Web searching and device discovery, ties more deeply into Microsoft’s SkyDrive cloud service, and bundles in Microsoft services and apps like Skype, Mail, and Xbox Video.

The OS update also provides native support for 3D printing for the first time.

Microsoft is billing Windows 8.1 as its best ever platform for multitasking and productivity, touting the ability to “display and use up to four apps side by side, flexible windows sizing for each app on the screen, the ability for one app to launch another app, and improved multi-monitor support so users can view the desktop or apps from the Windows Store on any or all monitors.”

Owners of Windows 8 computers and devices can download Windows 8.1 for free online at Microsoft’s newly redesigned Windows Store. Those currently running Windows XP, Windows Vista, Windows 7, or the Windows 8.1 Preview can visit this landing page(Opens in a new window) at Windows.com to find out how to upgrade to Windows 8.1.

For more, check out PCMag’s full review of Windows 8.1 and the slideshow above. Also see How to Install Windows 8.1 and 5 Tips for Using Windows 8.1 Like a Boss.