[8] Microsoft also claims that "WSL requires fewer resources (CPU, memory, and storage) than a full virtual machine" (a common alternative for using Linux in Windows), while also allowing the use of both Windows and Linux tools on the same set of files.

[10] Whereas Microsoft's previous projects and the third-party Cygwin had focused on creating their own unique Unix-like environments based on the POSIX standard, WSL aims for native Linux compatibility.

Instead of wrapping non-native functionality into Win32 system calls as Cygwin did, WSL's initial design (WSL 1) leveraged the NT kernel executive to serve Linux programs as special, isolated minimal processes (known as "pico processes") attached to kernel mode "pico providers" as dedicated system call and exception handlers distinct from that of a vanilla NT process, opting to reutilize existing NT implementations wherever possible.

WSL was no longer beta in Windows 10 version 1709 (Fall Creators Update), released on October 17, 2017.

[12] In 2017 Richard Stallman expressed fears that integrating GNU functionality into Windows will only hinder the development of free software, calling efforts like WSL "a step backward in the campaign for freedom.

"[13] 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.

[16] GPU support for WSL 2 to run GPU-accelerated machine learning was introduced in Windows build 20150.

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.

[19][18] The Windows Subsystem for Linux GUI (WSLg) was officially released at the Microsoft Build 2021 conference.

[8] The architecture was redesigned in WSL 2,[6] with a Linux kernel running in a lightweight virtual machine environment.

[37] Prerequisites for running WSLg include: LXSS Manager Service is the service in charge of interacting with the subsystem (through the drivers lxss.sys and lxcore.sys), and the way that Bash.exe (not to be confused with the Shells provided by the Linux distributions) launches the processes, as well as handling the Linux system calls and the binary locks during their execution.

Due to a total lack of Linux in WSL 1, kernel modules, such as device drivers, cannot be run.

It is possible to run some graphical (GUI) applications (such as Mozilla Firefox) by installing an X11 server within the Windows (host) environment (such as VcXsrv or Xming),[44] although not without caveats, such as the lack of audio support (though this can be remedied by installing PulseAudio in Windows in a similar manner to X11) or hardware acceleration (resulting in poor graphics performance).

[45][46] Microsoft stated WSL was designed for the development of applications, and not for desktop computers or production servers, recommending the use of virtual machines (Hyper-V), Kubernetes, and Azure for those purposes.

[7] In June 2020, a benchmark with 173 tests on WSL 2 (20H2) with an AMD Ryzen Threadripper 3970X showed an average of 87% of the performance of native Ubuntu 20.04 LTS.

[6] From Windows an IFS network redirector is provided for Linux guest file access using the UNC path prefix of \\wsl$.