Some two and a half years after its release, Windows 10 has finally overtaken Windows 7 in worldwide usage.
That's according to web analytics firm StatCounter, which puts Windows 10's share of Windows PCs at 42.78 percent, ahead of Windows 7's 41.86 percent.
Windows 10, which was released in July 2015, has climbed from a 32.84 percent share in January 2017, while Windows 7 declined from 47.46 percent in the period.
As those who closely track Windows market share know, there are several sources that offer these figures and they always differ due to different methodologies and varying sources of web traffic.
The other oft-quoted analytics firm, NetMarketShare, reports Windows 7 with an eight percent lead over Windows 10, though the gap has closed from 20 percent a year ago.
As ZDNet's Ed Bott has previously explained, NetMarketShare aims to measure daily unique users within its network, while StatCounter measures total traffic. NetMarketShare also weights the data by country, whereas StatCounter doesn't.
Meanwhile, the US Government analytics portal says 21.3 percent of 2.59 billion visitors in the past three months used Windows 10, compared with 19.8 percent Windows 7 devices. It was an even split between US and international visitors.
As StatCounter notes, there are geographical differences in when Windows 10 overtook Windows 7. In North America and the UK, Windows 10 took the lead in January 2017 and June 2016, respectively.
In Europe, the crossover happened in March 2017, while Windows 7 still has a 15 percent and 30 percent lead over Windows 10 in Asia and India, respectively.
Another figure Microsoft cares about is how many Windows 10 users are running the latest version, the Windows 10 Fall Creators Update.
According to AdDuplex, as of January, 74 percent of Windows 10 users are on the latest version, followed by 17 percent on the Creators Update.
A key group still holding on to Windows 7 are Microsoft's enterprise customers, which Microsoft hopes it can encourage to upgrade for Windows 10's superior security, which the company has argued on numerous occasions would have protected businesses from last year's WannaCry and NotPetya cyber-attacks.
In its latest pitch, it said from June to November 2017, Windows 7 devices were 3.4 times more likely to encounter ransomware than Windows 10 devices.
Nonetheless, StatCounter CEO Aodhan Cullen described Windows 10 surpassing Windows 7 as a "breakthrough for Microsoft".
"Windows 10 was launched at the end of July 2015 and Microsoft will be pleased to have put its Windows 8 experience behind it," he wrote.
"However, Windows 7 retains loyalty, especially among business users. Microsoft will be hoping that it can replace it a lot quicker than XP, launched back in August 2001, which only fell below five percent usage worldwide in June of 2017."
End of year report: Microsoft's free upgrade to Windows 10 got the operating system off to a fast start, but growth soon stalled. Future progress will depend on a flat PC market and commercial upgrades that enterprises may put off for another couple of years.