Windows 11 (original release)

Windows 11 is a major version of Microsoft Windows that was originally announced on 24 June 2021 and succeeds the Windows 10 family of operating systems. The initial Cobalt-based release has been generally available since 5 October 2021 as a free upgrade over Windows Update and includes a refreshed user interface, as well as other minor improvements over the Windows 10 May 2021 Update.

This version drops support for 32-bit x86 systems and devices which use BIOS firmware, leaving only the AMD64/x64 and ARM64 target platforms, although 32-bit user applications are still supported via WoW64. The operating system now also requires a system with 64-bit UEFI firmware that supports the Secure Boot specification and includes a Trusted Platform Module, which has been subject to controversy as it leaves many older systems that fully support Windows 10 ineligible for the free upgrade.

History
Rumors of a new major version of Windows were initially sparked by comments made by Panos Panay, Microsoft's chief product officer, and Satya Nadella, chairman of Microsoft, both talking about a next generation of Windows. "And soon, we will share one of the most significant updates to Windows of the past decade to unlock greater economic opportunity for developers and creators. I’ve been self-hosting it over the past several months, and I'm incredibly excited about the next generation of Windows. Our promise to you is this: we will create more opportunity for every Windows developer today and welcome every creator who is looking for the most innovative, new, open platform to build and distribute and monetize applications. We look forward to sharing more very soon."

- Satya Nadella at Microsoft Build 2021

References to a potential new version were unintentionally disclosed in Microsoft documentation weeks before the official announcement, including a mention of "Windows Sun Valley" in a description alongside Windows 10, telemetry documentation showing two separate updates both bearing the 21H2 version number, or a Windows 11 reference in accidentally published internal Azure taxonomy documentation. The aka.ms/windows11 redirect has also been found to exist in late May 2021, similarly to redirects for other major Windows releases.

A special event was held on 24 June 2021 where Microsoft officially announced Windows 11. Despite the company's great efforts to prevent any leaks prior to the event, build 21996 was shared online on 15 June, nine days before the keynote. The build includes Windows 11 branding, as well as a new Start menu and taskbar reminiscent of Windows 10X together with redesigned user interface widgets. Panos Panay later acknowledged the leak in an interview with The Verge, saying that it "was some early weird build".

The first Insider Preview build, 22000.51, was publicly released on 28 June to the Dev Channel and introduced several redesigned apps, as well as a refreshed login screen and further updates to the taskbar. The following preview builds are released on a weekly basis in the form of cumulative updates for build 22000. Windows 11 was introduced to the Beta Channel on 29 July with the re-release of build 22000.100, after which both channels now receive the same builds at the same time. However, most new features initially roll out only to users in the Dev Channel and aren't enabled for remaining users until a later build.

On 31 August, Microsoft announced that the first release of Windows 11 would ship on 5 October. Three days later, on 2 September, the new version was released to the Release Preview Channel for commercial PCs, while the Dev Channel was moved to the active development branch with the new Nickel builds. Prior to that, ineligible systems that were previously allowed to trial Windows 11 builds were removed from the Insider program, although they will still receive new builds in the lead up to general availability. The last pre-release build, Windows 11 build 22000.194, was published on 16 September. A week later, the build was released as an optional upgrade to the remaining users in the Release Preview channel and ultimately became the final build available on the date of general availability. The operating system was officially rolled out at midnight of 5 October in each local time zone.

System requirements
Following the announcement of Windows 11, the new version has been criticized for its large increase in minimum system requirements. According to Microsoft, the new operating system requires a 64-bit system with UEFI firmware that supports Secure Boot and includes a TPM 2.0 module. Additionally, the company has released a list of compatible processors, which notably only includes Intel's Coffee Lake family CPUs and newer, as well as AMD's Zen 2 processors (including select Zen+ models) and newer. The new requirements have been called out as artificial as they exclude many older computers from the Windows 11 upgrade on the premise of being old, even though they would likely be able to run Windows 11 with little to no performance issues.

Microsoft explained the new requirements as being guided by security, reliability and compatibility principles, although the company also promised to re-evaluate the list of eligible systems before release. The Intel Kaby Lake and AMD Zen 1 architectures were at one point considered for upgrade eligibility, however, Microsoft eventually opted to only support select Kaby Lake systems in the final release. The TPM 2.0 and CPU requirements were also temporarily unenforced for users enrolled in the Dev Channel as a limited exception in order to collect more data regarding the system requirements. The exception was discontinued on 31 August when all ineligible systems were dropped from the Insider program.

The raised requirements will only apply to upgrades via Windows Update. Installing Windows 11 manually by downloading the install media will be possible on unsupported systems using a workaround intended to allow businesses to evaluate the new version, although the company also stated that such systems will not be able to receive any future feature updates.

Default apps
Windows 11 has also been criticized because it is much harder there to set default apps, such as web browsers, media players and photo viewers. Users now need to set manually the defaults for file types and protocols. When an app notifies the user to set it as default, it now redirects to the File Types page of the new Settings. Mozilla fixed this issue in a version of Firefox, thanks to Reverse Engineering, and criticized Microsoft, as other developers of web browsers also did, for this tactic.

Development
The development process of Windows 11 is considerably different from previous releases. Microsoft had been working on the Cobalt codebase since October 2020, with preview builds being released to the Dev Channel with a weekly cadence for the most part. The channel was switched to the release branch in April 2021 with the introduction of build 21354. Around that time, the company also began work on the Windows 11 user experience in a separate  branch, which was bumped to the 216xx build range, whereas the public   branch was in the 213xx build range.

After the release of build 21390 in May 2021, the release branch was bumped to the 219xx build range and the main user interface work from the  was merged to it. The Cobalt core was considered complete since build 22000.1, although further work on the user experience continued in the refresh branch, which was bumped to the 221xx range. This work was being continuously merged to the  branch and released in the form of cumulative updates for build 22000 to the Dev Channel from build 22000.51 onwards.

List of known builds

 * This list only includes builds of the original Windows 11 release in October 2021. For builds from the active development branch that have been released to the Dev Channel since September 2021, see Nickel.