Microsoft just took another big step toward the release of Windows 10 — and revealed it will be free for many current Windows users.

The company unveiled the Windows 10 consumer preview on Wednesday, showcasing many new features in the latest version of the operating system that powers the vast majority of the world's desktop PCs. It also surprised the tech world with an ambitious take on virtual reality, called Windows Holographic, powered by a new kind of device called the HoloLens.

The developer preview has been available since Microsoft first announced Windows 10 in the fall, but it was buggy, limited in scope and very light on new features.

Windows 10 will be free for existing Windows users running versions of the OS, going back to Windows 7. That includes Windows 7, 8, 8.1 and Windows Phone. Microsoft specified the Windows 10 upgrade would be free for the first year of release, but users would need to pay for it after that. However, Microsoft will support the upgrade for the "lifetime of the device," according to the announcement.

"We want to make Windows 10 the most loved release of Windows," Microsoft CEO Satya Nadella said at the event. ""We are going to have services everywhere. But when it comes to Windows, we're not bolting on apps."

One of the biggest announcements was a new web browser for Windows 10, codenamed Project Spartan. It'll be the primary browser in Windows 10 and will be available on PCs, tablets and phones.

Microsoft's Corporate Vice President of the Operating Systems Group, Joe Belfiore, showed off some of the new features in Windows 10. Microsoft had already announced it would bring back the much-missed Start Menu, but Belfiore revealed it would also have a full-screen mode that includes more of the Windows 8 Start screen. He also said Windows machines would go back and forth between to two menus in a way that wouldn't confuse people.

Windows 10 will have two versions of the resurrected Start Menu, a familiar one with some "Modern" tiles and a full-screen version show here. Image: Microsoft

Belfiore also showed a new notification center for Windows, which puts a user's notifications in an Action Center menu that can appear along the right side, similar to how notifications work in Apple OS X.

We also learned more about Continuum, the feature in Windows 10 that will help so-called hybrid devices change from mode to mode. Removing a keyboard from a tablet like the Surface Pro 3, say, will call up a dialog box asking if the user wants to switch to tablet mode.

Cortana comes to the PC

Microsoft is also bringing Cortana to the PC with Windows 10. Users will be able to access it via a search bar next to the Windows logo in the taskbar.

Describing Cortana as an "extra member of the family," Belfiore showed how users could ask her to play music, answer queries ("Who will win the Super Bowl?" "Show me photos from December") and even launch apps and open specific files, like a PowerPoint deck you've been working on.

Belfiore showed how Windows 10 would work on devices smaller than 8 inches, which would have a special version of the OS tuned to the precise touch capabilities needed. Calling such devices great "companions" to a PC, they'll have integrated messaging, including Skype, which would work together with apps on the PC.

As an example of Universal Windows Apps, which are apps that provide a multi-modal experience across devices, Belfiore showed off revamped mobile versions of Microsoft Office.



The Office suite for Windows 10 will include a new Outlook mail client, and the Office apps will work together across devices — when you want to project a PowerPoint presentation from a phone to a PC, for example.

Windows 10 will also have a new way to handle photos, giving users a "collection" view of photos that indexes all of a user's photos across devices, and ignores duplicates in a thumbnail view. It will also automatically enhance some photos, in a manner similar to Google's auto-awesome feature.

Project Spartan, the new browser revealed publicly for the first time Wednesday, allows users to "draw" directly on a web page for quick sharing of notes. It includes a fully integrated reading list that follows a user across devices, as well as a built-in PDF viewer. Cortana is also built into Spartan.

Project Spartan is the new web browser for Windows 10. Image: Microsoft

Xbox head Phil Spencer also revealed that there would be an Xbox app for Windows 10, and that gaming on the platform would be "more social and interactive" than before. Voice chat and text chat among players would work across platforms. Windows 10 apps will be easily transferrable to the Xbox One, he said, and Xbox One owners will be able to transfer gameplay across Windows devices for many games.

The consumer preview version of Windows 10 will be available for PCs starting next week, and for phones in February. Some of the Windows 10 features Microsoft showed at the event would not immediately be available in preview builds of the software, but would roll out in the next 3 to 4 months.

Alex Kipman, one of the architects behind Microsoft Kinect, revealed the biggest surprise of the event: Windows Holographic, an ambitious project that combines aspects of virtual reality, holography, augmented reality and wearable technology. The experience is powered by a new device called the HoloLens, a headset that can immerse the wearer in a virtual experience as well as create individual "holograms" overlayed on real objects.

The thrust of Windows 10

Microsoft Executive Vice President of Operating Systems Terry Myerson revealed that 1.7 million people had downloaded the Windows 10 developer preview, giving Microsoft more than 800,000 pieces of feedback.

Myerson mentioned three main goals for Windows 10: letting users transfer seamlessly from device to device, instilling trust in users, and providing the most natural ways to interact with devices.

"You should be able to to print with a flick, or transfer a Skype call with a simple, intuitive gesture," Myerson said. "It's important that our users' privacy is protected, and that they trust the experience."

See also: Cortana is making the leap to Windows 10

Windows 10 has been anticipated for a long time. Originally codenamed "Threshold" by Microsoft, the OS was rumored to be called Windows 9 — which would make sense, given that the last release was Windows 8. But Microsoft decided to skip a version number, ostensibly to convey the weight of the upgrade.

The new OS is also intended to address complaints about Windows 8, and later 8.1. While Windows 8's touch-first approach worked well for tablets, it could be unwieldy for traditional mouse-and-keyboard setups, and some found the disappearance of traditional user-interface elements — notably the Start Menu — jarring. Windows 10 reasserts many traditional Windows design elements (including the Start Menu), but also provides a platform that Microsoft can build on for the future.

Microsoft hasn't yet set a date for the general release of Windows 10, but it's expected to launch in the fall.

Correction: Windows 10 will be a one-time upgrade, free for the first year of release, and there will not be a subscription model attached, as this post initially reported.