<P> In April 2014, at the Build Conference, Microsoft's Terry Myerson unveiled an updated version of Windows 8.1 that added the ability to run Windows Store apps inside desktop windows and a more traditional Start menu in place of the Start screen seen in Windows 8 . The new Start menu takes after Windows 7's design by using only a portion of the screen and including a Windows 7 - style application listing in the first column . The second column displays Windows 8 - style app tiles . Myerson said that these changes would occur in a future update, but did not elaborate . Microsoft also unveiled the concept of a "universal Windows app", allowing Windows Store apps created for Windows 8.1 to be ported to Windows Phone 8.1 and Xbox One while sharing a common codebase, with an interface designed for different device form factors, and allowing user data and licenses for an app to be shared between multiple platforms . Windows Phone 8.1 would share nearly 90% of the common Windows Runtime APIs with Windows 8.1 on PCs . </P> <P> Screenshots of a Windows build which purported to be Threshold were leaked in July 2014, showing the previously presented Start menu and windowed Windows Store apps followed by a further screenshot in September 2014 of a build identifying itself as "Windows Technical Preview", numbered 9834, showing a new virtual desktop system, a notification center, and a new File Explorer icon . </P> <P> Threshold was officially unveiled during a media event on September 30, 2014, under the name Windows 10; Myerson said that Windows 10 would be Microsoft's "most comprehensive platform ever", providing a single, unified platform for desktop computers, laptops, tablets, smartphones, and all - in - one devices . He emphasized that Windows 10 would take steps towards restoring user interface mechanics from Windows 7 to improve the experience for users on non-touch devices, noting criticism of Windows 8's touch - oriented interface by keyboard and mouse users . Despite these concessions, Myerson noted that the touch - oriented interface would evolve as well on 10 . In describing the changes, Joe Belfiore likened the two operating systems to electric cars, comparing Windows 7 to a first - generation Toyota Prius hybrid, and Windows 10 to an all - electric Tesla ‍--‌considering the latter to be an extension of the technology first introduced in the former . </P> <P> In regards to Microsoft naming the new operating system Windows 10 instead of Windows 9, Terry Myerson said that "based on the product that's coming, and just how different our approach will be overall, it wouldn't be right to call it Windows 9 ." He also joked that they could not call it "Windows One" (alluding to several recent Microsoft products with a similar brand, such as OneDrive, OneNote, and Xbox One) because Windows 1.0 already existed . Tony Prophet, Microsoft Vice President of Windows Marketing, said at a San Francisco conference in October 2014 that Windows 9 "came and went", and that Windows 10 is not "an incremental step from Windows 8.1," but "a material step . We're trying to create one platform, one eco-system that unites as many of the devices (sic) from the small embedded Internet of Things, through tablets, through phones, through PCs and, ultimately, into the Xbox ." </P>

Which of the following was introduced with windows 10