Owners of Windows 7 and 8 will be able to upgrade to Windows 10 for free when it is released later this year, Microsoft announced at their big Windows 190 even today. A consumer preview release will be available for free shortly, but a date for the finished version has not been announced yet.
Among the other news is that Internet Explorer will be retired as of Windows 10 and be replaced by a new modern browser (code name Spartan) created from the ground up. The start menu is back, and Cortana (Microaoft answer to Apple’s Siri, and already available on Windows phones) will be available for the desktop as well. Talking about desktop, Windows 10 will support multiple desktops, similar to what Linux users have been able to enjoy for years.
At the event Microsoft also demonstrated a holographic headset. A new API allows developers to create augmented reality applications that can interact with the new headset/goggles.