windows 10 (codenamed Threshold) is an upcoming operating system developed by microsoft as part of the windows NT family of operating systems. First presented in April 2014 at the Build Conference, it is scheduled to be released in mid-2015, but microsoft has made the windows 10 preview available for everyone.
Important
Remember, trying out an early build like this can be risky. That's why we recommend that you don't install the preview on your primary home or business PC. Unexpected PC crashes could damage or even delete your files, so you should back up everything.
If you want to stop using windows 10 Insider Preview and return to your previous version of windows, you'll need to reinstall your previous version from the recovery or installation media that came with your PC – typically a DVD. If you don't have recovery media, you might be able to create a USB recovery drive.
After you've installed Windows 10 Insider Preview, you won't be able to use the recovery partition on your PC to go back to your previous version of Windows.
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