Satya Nadella, CEO of Microsoft, speaks with Herbert Diess, CEO of Volkswagen AG (not pictured), about a joint project between the two companies called the Volkswagen Automotive Cloud in Berlin on Feb. 27, 2019.

Microsoft's Windows 10 is getting bigger.

The operating system for desktop PCs, internet-connected devices and other systems is now running on more than 800 million devices, according to a website that Microsoft executive Yusuf Mehdi pointed out on Twitter on Thursday.

The total is up from 700 million in September, and it suggests that the newest rendition of Windows could now be the most widely deployed version of Windows, ahead of Windows 7 and other versions.

Although Microsoft -- the most valuable publicly traded company in the world -- has shifted to focus more on cloud and third-party platforms under CEO Satya Nadella, Windows is still a key element of the company, contributing almost 15 percent of total revenue in the fourth quarter. It's also a notable contributor of operating income, as former CEO Steve Ballmer pointed out last year.

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Microsoft introduced Windows 10 in mid-2015. The company originally was aiming to have it running on 1 billion devices within three years of release, but one year in, Mehdi indicated that it would take longer. The company crossed the halfway point in mid-2017.

In October, Microsoft said that there were 1.5 billion devices running Windows. If that's still true, more than 50 percent would be using Windows 10.

Microsoft is preparing to roll out the first of two major annual Windows 10 updates, known as 19H1, in the coming weeks. Among the additions is a light theme affecting the desktop wallpaper and other elements.

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