Microsoft's Corporate Vice President of Windows and Devices Yusuf Mehdi announced the latest count via a blog post on January 4. Mehdi noted that Microsoft added more than 40 percent of the total number of active devices running Windows 10 since Black Friday.
Back in October, Microsoft didn't yet have any Windows 10 phones in market in October, nor had it yet pushed the Xbox One update that brought the Windows 10 operating system to Xbox One. Microsoft's blog post today doesn't explicitly state whether the company is counting the Lumia 950, 950 XL and 550 (all running Windows 10 Mobile) and Xbox One consoles as part of the 200 million device total. I am betting the company is. I've asked to see if I can get official clarification.
Update: A company spoksperson confirmed the 200 million figure includes Xbox One consoles. And "active" means Windows 10 devices that have been "active" in the last 28 days, the spokesperson said.
Of the 200 million devices running Windows 10, more than 22 million of those are on devices run by enterprise and education customers, Microsoft officials said. The company claims 76 percent of its enterprise customers are in "active pilots" of Windows 10.
Mehdi also said today that Windows 10 is on the "fastest growth trajectory of any version of Windows -- ever." He said it outpaced Windows 8 by nearly 400 percent, and Windows 7 by nearly 140 percent.
It's tough to do an apples-to-apples comparison, as Microsoft reported Windows 8 numbers as "licenses sold," which meant copies sold into the channel, not copies activated on devices. Windows 8 hit the 200 million licenses-sold mark four months after the operating system's release.
For users with automatic updates enabled, the "Recommended" setting may cause the Windows 10 upgrade to automatically initiate on their devices. However, users will not be upgraded to Windows 10 until they proactively choose to do so, even once it's pushed as a Recommended Update, Microsoft officials have said.
On the devices side of the house, starting tomorrow, users will be able to pre-order the Microsoft Surface Book in Austria, Australia, UK, France, Germany, Switzerland, and New Zealand. It also will be "coming soon" to Japan, today's blog post says, as will the Surface Pro to India (which will happen "in the coming weeks"). The Surface Book was made available for preorder recently in Hong Kong and China.
Mehdi also says "demand outstripped supply" for the new Lumia 950 and 950 XL phones and that Microsoft is working to restock those devices in stores where they sold out.