This technical report presents an analysis of the global operating system (OS) market share for mobile and desktop platforms as of May 2025. It categorizes the OS into two main segments: Mobile OS, including Android and iOS, and Desktop OS, which encompasses Windows, macOS, Linux, and ChromeOS. The report details the market share statistics, highlighting that Android leads the mobile OS market with 72.72%, while Windows dominates the desktop OS market with 70.21%. It discusses the factors influencing these trends, including consumer habits, enterprise needs, and hardware compatibility issues. The report also examines the adoption rates of various OS versions, particularly Windows 10 and Windows 11, noting the challenges organizations face in transitioning to newer systems. Additionally, it addresses the implications of these trends for businesses and developers, emphasizing the importance of understanding the evolving tech landscape and the need for cross-platform compatibility.