Explore the journey of open sourcing Windows Subsystem for Linux (WSL) at Microsoft in this 25-minute conference talk from Ubuntu Summit 25.10. Learn from WSL Dev Lead and Product Manager as they chronicle WSL's evolution from initial concepts to becoming a fully open source component of Windows. Discover WSL's unique architecture and understand Microsoft's approach to building a healthy open source repository that effectively collaborates with the broader open source community. Gain insights into the challenges and strategies involved in transitioning a Windows feature to open source, and understand how this transformation aims to enhance developer experiences across platforms. The session provides valuable perspectives on corporate open source initiatives and the technical considerations involved in making proprietary software components accessible to the community.