Windows 10 (original release)

This article is about the original release of Windows 10 from July 2015. For the overall operating system series, see Windows 10.

Windows 10 (codenamed Threshold; retroactively referred to as version 1507 in documentation) is the successor to Windows 8.1 and the first release of the Windows 10 series, released on 29 July 2015 as a free upgrade for Windows 7 and Windows 8.x users until 29 July 2016 through the Get Windows 10 app. It was intended to address some of the complaints that were made in response to the user interface in Windows 8 and Windows 8.1. It has gained largely positive reviews and has easily exceeded the market share that Windows 8 gained in the same period.

Very early documents refer to this version as Windows 8.2, Windows 9, or Windows TH. According to an unverified rumor, the name "Windows 9" was rejected due to certain apps interpreting an operating system name beginning with that string as belonging to the Windows 9x series. It is more likely that the name change was due to marketing potential. Microsoft explained the skip from number 8 to 10 as reinforcing the importance of Windows 10 as the last major version of Windows, although the company would later break this promise with the release of Windows 11 in 2021.

The Windows Insider Program was introduced with this version, which boosted the company's engagement with its beta testers as well as distributing new releases more frequently than the prior beta testing initiatives. The Insider program was also the first time Windows Update was used to publicly distribute full new builds of the operating system, as opposed to simple patches applied on top of the same build.

Windows 8.2
Before Windows 10 was planned, Microsoft planned a version of windows known as “Windows 8.2”, it was codenamed “Dark Blue” and it was going to add the new Start menu (Pre XAML), along with animation and feature enhancements. At the time, Microsoft also began work on windows 10, meaning all the work put into 8.2 became Windows 10.

Windows Update ESD listing
See here for a list of Windows 10 ESD files that have been gathered from the Windows Update infrastructure.''

Technical Preview
The Technical Preview was the first phase of the Windows Insider program. The first official build released was 9841, and the last official build released during this phase was build 10061.

Insider Preview
This phase of development began with build 10074, which was a quality build, at least going by the standards set by 10041 and 10049. The final phase of TH1 Insider Preview development ended with build 10166, which was extremely close to the RTM build, build 10240.