We've been hearing about Microsoft's vision of universal apps for years -- apps that can be written once and run on a wide variety of devices -- but with Windows 10 it's finally becoming a reality. During today's massive Windows 10 event, Microsoft's operating system heads Terry Myerson and Joe Belfiore mentioned several instances of how universal apps will fit into the Windows ecosystem. Windows 10 apps will eventually show up on the Xbox One, Myerson noted, and Belfiore also showed off how Microsoft Office apps seamlessly scale from phones (which will also run Windows 10) to PCs. The notion of universal apps may seem a tad boring, but it's essential to making developers latch onto this new Windows entry in a way they never did for Windows 8. After all, it's much easier to convince someone to build an app for your platform when it can be easily deployed across all sorts of devices (and it makes up for the weak mobile ecosystem).