Almost three years after Windows 10 was launched, the number of computers running the OS has overtaken Windows 7 for the first time, according to web analytics firm StatCounter.

The company’s research arm StatCounter Global Stats found that Windows 10 PCs accounted for 42.78% of worldwide internet usage by Windows computers, compared to 41.86% running Windows 7.

Since Windows 10’s launch in 2015, Microsoft has made a concerted effort to get people using older versions of Windows to upgrade.

Microsoft ran a year-long free Windows 10 upgrade program for Windows 7 and 8.1 users until July 2016, and has since concentrated on persuading businesses to begin the transition to its flagship OS. The latest figures from Microsoft showed there were 600 million active monthly users of Windows 10.

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“This is a breakthrough for Microsoft,” said Aodhan Cullen, CEO of StatCounter.

“Windows 10 was launched at the end of July 2015 and Microsoft will be pleased to have put its Windows 8 experience behind it. However, Windows 7 retains loyalty especially amongst business users.”

Cullen said Microsoft will want to avoid a repeat of what happened with Windows XP, where there were instances of organizations leaving the transition until just before support ended in 2014, with some big names, such as the US Navy, paying millions to stick with XP after Extended Support ended.

“Microsoft will be hoping that it can replace it [Windows 7] a lot quicker than XP, launched back in August 2001, which only fell below 5% usage worldwide in June of 2017,” said Cullen.

StatCounter’s desktop OS figures vary widely according to the region, with Windows 10 overtaking 7 in North America in January 2017, and in the UK in June 2016.

Nevertheless, the speed with which Windows 10 has been adopted has been slower than Microsoft initially anticipated. In 2015, the company set out its goal to have Windows 10 running on 1 billion devices within two to three years release. Microsoft officials conceded last year that it would take longer to hit the 1 billion mark, likely due to the failure of Windows 10 to gain traction as a smartphone OS.

And despite the free Windows 10 upgrade offer, StatCounter’s figures show that it has taken Windows 10 slightly longer to usurp Windows 7 than it did for Windows 7’s userbase to outgrow that of the then popular Windows XP.

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StatCounter’s figures also contradict statistics gathered by analytics firm NetMarketShare, which found that Windows 7 is still more popular than Windows 10.

NetMarketShare figures for January 2018 estimate that 34.29% of web users were running Windows 10 and 42.39% were on Windows 7. However, the US Government analytics portal backs StatCounter, showing Windows 10 PCs as accounting for 21.3% of visits to government websites over the past 90 days, with 19.9% being Windows 7 machines.

Part of the difference between NetMarketShare’s and StatCounter’s figures, and why StatCounter’s findings might want to be taken with a pinch of salt, lies in the difference in how they measure web traffic.

NetMarketShare stats count every user equally, while StatCounter gives extra weight to heavy web users, due to the fact that NetMarketShare attempts to measure daily unique users, while StatCounter measures total traffic.

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