This document discusses Microsoft's evolving approach to open source software and cloud computing over the past 20 years. It notes that while Microsoft was once opposed to open source, it has increasingly embraced and contributed to open source projects like .NET and Linux. It also discusses how Microsoft's cloud platform Azure has adopted many open source technologies and allows development with open source languages and tools. The document argues that today, Microsoft supports a fully open development model across Windows, Linux and MacOS with technologies like .NET Core, Docker and GitHub.