Now playing: Watch this: Windows 10 is a free upgrade for existing Windows customers

Microsoft will offer free upgrades to Windows 10 -- the next version of its operating system -- first for Windows 8.1 users and then for Windows 7 users, the company announced Wednesday.

In the first year the software is available, the company will upgrade any devices running Windows 8 to Windows 10 for free, according to Terry Myerson, Microsoft's executive vice president of operating systems. The free upgrade will also apply to Windows 7 devices and Windows Phone 8.1 devices.

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The free upgrade is only available for the first year. Microsoft has yet to announce the software's price for the upgrade after that one-year window.

"We think of Windows as a service," Myerson said during Microsoft's Windows 10 unveiling event in Redmond, Wash. "Now developers can target every single Windows device."

The move is likely designed to convince consumers that Windows is worth the effort. Windows 10 is an attempt to wipe the slate clean after missteps with Windows 8, including a new start menu that attracted complaints from PC users, who sorely missed the traditional menu.

More than half of all desktops in the world still run Windows 7. Almost 20 percent still run Windows XP, a 14-year-old operating system. Windows 8.1 has yet to reach 10 percent.

Hardware companies have increasingly been giving away software upgrades to keep their users tied to their ecosystems. Apple, for example, has made both its Mac OS and iOS free, as well as many of its productivity and photo management tools.

With Windows 10, Microsoft hopes it can inspire customers to seek out its products, rather than feeling like they have to use them.

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Pulling that off is no easy feat, but it's critical to Microsoft's future. The company is aggressively simplifying its entire platform under the "one Windows" vision of CEO Satya Nadella, which promises to make this next iteration of Windows run on every desktop, laptop, tablet and smartphone. To make this work, Microsoft is readying a significant change to how it and its developer community will deliver, manage and build next-generation software for every device -- with one store and with one way for consumers to download and access programs across screens.

Correction at 10:35 a.m. PT: The one year of free upgrades applies to Windows 7, Windows 8.1 and Windows Phone 8.1 devices.

This is a developing story. For real-time updates, follow the CNET live blog and check out our full coverage of today's Windows 10 news.