Windows 10 Mobile review: Windows on phones gets rebooted. Again.

One way or another, Microsoft has been promising Windows 10 Mobile for years.

References to "Windows Everywhere," the notion that some version of Windows could run on everything from PCs to servers to cars, can be found as far back as 1998, when Redmond was hawking Windows 98, Windows NT 4, and Windows CE. Per Paul Thurrott, the plan was conceived as "NT Everywhere;" the broader ambition of "Windows Everywhere" soon made space for the Windows 9x and Windows CE variants.

How the idea was expressed varied—in 2009, for example, Microsoft called it "Three Screens and a Cloud"—but the notion of having a Windows platform for any device has endured.