The word of the day for Microsoft is: platform. On Wednesday, CEO Satya Nadella and his lieutenants ran through a nearly three-hour keynote presentation to kick off the company’s annual Build developer conference in San Francisco, and no word came from executive lips more often than “platform.”Nadella called Microsoft a platform company. Terry Myerson, Microsoft’s executive vice president of operating systems, only referred to Windows 10 as a platform. Microsoft Azure, a cloud service to build and deploy apps on? Yes, it’s also a platform. HoloLens, Microsoft’s augmented reality headset, which runs Windows 10, was even positioned as a platform that’ll define the future of how we interact with computers—taking on both wearables and virtual reality at once.