Bill Gates and Paul Allen formed Microsoft in 1975 to focus on developing the MS-DOS operating system. Over time, Microsoft introduced graphical user interface operating systems like Windows to make computers easier to use. Key versions included Windows 95 which introduced the Start menu and taskbar, and Windows 10 which unified the desktop and mobile interfaces and introduced features like Cortana and Continuum Mode. Windows has evolved from a command-line interface to one optimized for touchscreens, with Microsoft aiming to deliver a consistent experience across all device types.