Microsoft's Windows Subsystem for Linux (WSL) was introduced in the Windows 10 Anniversary Update of 2016, allowing users to run Linux applications within Windows. The company has improved WSL over the years, adding features like GPU and audio support. At the recent Build developer conference, Microsoft announced that nearly all of WSL will transition to open source, marking the resolution of the first issue raised on GitHub in 2016. Senior Software Engineer Pierre Boulay highlighted the importance of community contributions to WSL's development. However, two components will remain closed-source: the lxcore.sys kernel driver and the p9rdr.sys and p9np.dll files, with no timeline provided for their potential open-sourcing.