shell) was supported. WSL beta was also called "Bash on Ubuntu on Windows" or "Bash on Windows". WSL was no longer beta in Windows 10 version 1709 (Fall Creators Update), released on October 17, 2017. Multiple Linux distributions could be installed and were available for install in the Windows Store. In 2017 Richard Stallman expressed fears that integrating Linux functionality into Windows will only hinder the development of free software, calling efforts like WSL "a step backward in the campaign for freedom." Though WSL (via this initial design) was much faster and arguably much more popular than the previous UNIX-on-Windows projects, Windows kernel engineers found difficulty in trying to increase WSL's performance and syscall compatibility by trying to reshape the existing NT kernel to recognize and operate correctly on Linux's API. At a Microsoft Ignite conference in 2018, Microsoft engineers gave a high-level overview of a new "lightweight" Hyper-V VM technology for containerization where a virtualized kernel could make direct use of NT primitives on the host. In 2019, Microsoft announced a completely redesigned WSL architecture (WSL 2) using this lightweight VM technology hosting actual (customized) Linux kernel images, claiming full syscall compatibility. Microsoft announced WSL 2 on May 6, 2019, and it was shipped with Windows 10 version 2004. It was also backported to Windows 10 version 1903 and 1909. GPU support for WSL 2 to do GPU-accelerated machine learning was introduced in Windows build 20150. GUI support for WSL 2 to run Linux applications with graphical user interfaces (GUIs) was introduced in Windows build 21364. Both of them are shipped in Windows 11. In April 2021, Microsoft released a Windows 10 test build that also includes the ability to run Linux graphical user interface (GUI) apps using WSL 2 and CBL-Mariner. The Windows Subsystem for Linux GUI (WSLg) was officially released at the Microsoft Build 2021 conference. It is included in Windows 10 Insider build 21364 or later. Microsoft introduced a Windows Store version of WSL on October 11, 2021, for Windows 11, and WSL reached version 1.0.0 on November 16, 2022. Notable releases Features WSL is available in Windows Server 2019 and in versions of Windows 10 from version 1607, though only in 64-bit versions. Microsoft envisages WSL as "primarily a tool for developers – especially web developers and those who work on or with open source projects". In September 2018, Microsoft said that "WSL requires fewer